Methods and Functions

Displays an Alert dialog box with a message and an OK button.

Syntax

alert("message")

message is any string or a property of an existing object.

Description

Use the alert method to display a message that does not require a user decision. The message argument specifies a message that the dialog box contains.

Although alert is a method of the window object, you do not need to specify a windowReference when you call it. For example, windowReference.alert() is unnecessary.

Method of

window

Examples

In the following example, the testValue() function checks the name entered by a user in the text object of a form to make sure that it is no more than eight characters in length. This example uses the alert method to prompt the user to enter a valid value.

function testValue(textElement) {
   if (textElement.length > 8) {
      alert("Please enter a name that is 8 characters or less")
   }
}

Name: <INPUT TYPE="text" NAME="userName"
   onBlur="testValue(userName.value)">

See also

Creates an HTML anchor that is used as a hypertext target.

Syntax

text.anchor(nameAttribute)

text is any string or a property of an existing object.
nameAttribute is any string or a property of an existing object.

Description

Use the anchor method with the write or writeln methods to programatically create and display an anchor in a document. Create the anchor with the anchor method, then call write or writeln to display the anchor in a document.

In the syntax, the text string represents the literal text that you want the user to see. The nameAttribute string represents the NAME attribute of the <A> tag.

Anchors created with the anchor method become elements in the anchors array. See the anchor object for information about the anchors array.

Method of

string

Examples

The following example opens the msgWindow window and creates an anchor for the Table of Contents:

The previous example produces the same output as the following HTML:

See also

Returns the arc sine (in radians) of a number.

Syntax

Math.asin(number)

number is a numeric expression between -1 and 1, or a property of an existing object.

Description

The asin method returns a numeric value between -pi/2 and pi/2 radians. If the value of number is outside the suggested range, the return value is always 0.

Method of

Math

Examples

// Displays the value 1.570796326794897 (pi/2)
document.write("The arc sine of 1 is " + Math.asin(1))

// Displays the value -1.570796326794897 (-pi/2)
document.write("<P>The arc sine of -1 is " + Math.asin(-1))

// Displays the value 0 because the argument is out of range
document.write("<P>The arc sine of 2 is " + Math.asin(2))

See also

Returns the arc tangent (in radians) of a number.

Syntax

Math.atan(number)

number is either a numeric expression or a property of an existing object, representing the tangent of an angle.

Description

The atan method returns a numeric value between -pi/2 and pi/2 radians.

Method of

Math

Examples

// Displays the value 0.7853981633974483
document.write("The arc tangent of 1 is " + Math.atan(1))

// Displays the value -0.7853981633974483
document.write("<P>The arc tangent of -1 is " + Math.atan(-1))

// Displays the value 0.4636476090008061
document.write("<P>The arc tangent of .5 is " + Math.atan(.5))

See also

Loads the previous URL in the history list.

Syntax

history.back()

Description

This method performs the same action as a user choosing the Back button in the Navigator. The back method is the same as history.go(-1).

Method of

history

Examples

<P><INPUT TYPE="button" VALUE="< Back"
   onClick="history.back()">
<P><INPUT TYPE="button" VALUE="> Forward"
   onClick="history.forward()">

See also

Causes a string to be displayed in a big font as if it were in a <BIG> tag.

Syntax

stringName.big()

stringName is any string or a property of an existing object.

Description

Use the big method with the write or writeln methods to format and display a string in a document.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.small())
document.write("<P>" + worldString.big())
document.write("<P>" + worldString.fontsize(7))

The previous example produces the same output as the following HTML:

See also

Causes a string to blink as if it were in a <BLINK> tag.

Syntax

stringName.blink()

stringName is any string or a property of an existing object.

Description

Use the blink method with the write or writeln methods to format and display a string in a document.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())

The previous example produces the same output as the following HTML:

See also

Removes focus from the specified object.

Syntax

1. passwordName.blur()
2. selectName.blur()
3. textName.blur()
4. textareaName.blur()

passwordName is either the value of the NAME attribute of a password object or an element in the elements array.
selectName is either the value of the NAME attribute of a select object or an element in the elements array.
textName is either the value of the NAME attribute of a text object or an element in the elements array.
textareaName is either the value of the NAME attribute of a textarea object or an element in the elements array.

Description

Use the blur method to remove focus from a specific form element.

Method of

password, select, text, textarea

Examples

The following example removes focus from the password element userPass:

userPass.blur()

<INPUT TYPE="password" NAME="userPass">

See also

Causes a string to be displayed as bold as if it were in a <B> tag.

Syntax

stringName.bold()

stringName is any string or a property of an existing object.

Description

Use the bold method with the write or writeln methods to format and display a string in a document.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())

The previous example produces the same output as the following HTML:

<BLINK>Hello, world</BLINK>
<P><B>Hello, world</B>
<P><I>Hello, world</I>
<P><STRIKE>Hello, world</STRIKE>

See also

Returns the least integer greater than or equal to a number.

Syntax

Math.ceil(number)

number is any numeric expression or a property of an existing object.

Method of

Math

Examples

//Displays the value 46
document.write("The ceil of 45.95 is " + Math.ceil(45.95))

//Displays the value -45
document.write("<P>The ceil of -45.95 is " + Math.ceil(-45.95))

See also

Returns the character at the specified index.

Syntax

stringName.charAt(index)

stringName is any string or a property of an existing object.
index is any integer from 0 to stringName.length - 1, or a property of an existing object.

Description

Characters in a string are indexed from left to right. The index of the first character is 0, and the index of the last character is stringName.length - 1. If the index you supply is out of range, JavaScript returns an empty string.

Method of

string

Examples

var anyString="Brave new world"

document.write("The character at index 0 is " + anyString.charAt(0))
document.write("The character at index 1 is " + anyString.charAt(1))
document.write("The character at index 2 is " + anyString.charAt(2))
document.write("The character at index 3 is " + anyString.charAt(3))
document.write("The character at index 4 is " + anyString.charAt(4))

See also

Clears the document in a window.

Syntax

document.clear()

Description

The clear method empties the content of a window, regardless of how the content of the window has been painted.

Method of

document

Examples

When the following function is called, the clear method empties the contents of the msgWindow window:

function windowCleaner() {
   msgWindow.document.clear()
   msgWindow.document.close()
}

See also

Cancels a timeout that was set with the setTimeout method.

Syntax

clearTimeout(timeoutID)

timeoutID is a timeout setting that was returned by a previous call to the setTimeout method.

Description

See the description for the setTimeout method.

Method of

frame, window

Examples

See the examples for the setTimeout method.

See also

Simulates a mouse click on the calling form element.

Syntax

1. buttonName.click()
2. radioName[index].click()

3. checkboxName.click()

buttonName is either the value of the NAME attribute of a button, reset, or submit object or an element in the elements array.
radioName is the value of the NAME attribute of a radio object or an element in the elements array.
index is an integer representing a radio button in a radio object.
checkboxName is either the value of the NAME attribute of a checkbox object or an element in the elements array.

Description

The effect of the click method varies according to the calling element:

Method of

button, checkbox, radio, reset, submit

Examples

The following example toggles the selection status of the first radio button in the musicType radio object on the musicForm form:

document.musicForm.musicType[0].click()

The following example toggles the selection status of the newAge checkbox on the musicForm form:

document.musicForm.newAge.click()

Closes an output stream and forces data sent to layout to display.

Syntax

document.close()

Description

The close method closes a stream opened with the document.open() method. If the stream was opened to layout, the close method forces the content of the stream to display. Font style tags, such as <BIG> and <CENTER>, automatically flush a layout stream.

The close method also stops the "meteor shower" in the Netscape icon and displays "Document: Done" in the status bar.

Method of

document

Examples

function windowWriter1() {
   var myString = "Hello, world!"
   msgWindow.document.open()
   msgWindow.document.write(myString + "<P>")
   msgWindow.document.close()
}

See also

Closes the specified window.

Syntax

windowReference.close()

windowReference is a valid way of referring to a window, as described in the window object.

Description

The close method closes the specified window. If you call close without specifying a windowReference, JavaScript closes the current window.

In event handlers, you must specify window.close() instead of simply using close(). Due to the scoping of static objects in JavaScript, a call to close() without specifying an object name is equivalent to document.close().

Method of

window

Examples

Any of the following examples close the current window:

window.close()
self.close()
close()

The following example closes the messageWin window:

messageWin.close()

This example assumes that the window was opened in a manner similar to the following:

messageWin=window.open("")

See also

Displays a Confirm dialog box with the specified message and OK and Cancel buttons.

Syntax

confirm("message")

message is any string or a property of an existing object.

Description

Use the confirm method to ask the user to make a decision that requires either an OK or a Cancel. The message argument specifies a message that prompts the user for the decision. The confirm method returns true if the user chooses OK and false if the user chooses Cancel.

Although confirm is a method of the window object, you do not need to specify a windowReference when you call it. For example, windowReference.confirm() is unnecessary.

Method of

window

Examples

This example uses the confirm method in the confirmCleanUp() function to confirm that the user of an application really wants to quit. If the user chooses OK, the custom cleanUp() function closes the application.

function confirmCleanUp() {
   if (confirm("Are you sure you want to quit this application?")) {
      cleanUp()
   }
}

<INPUT TYPE="button" VALUE="Quit" onClick="confirmCleanUp()">

See also

Returns the cosine of a number.

Syntax

Math.cos(number)

number is a numeric expression representing the size of an angle in radians, or a property of an existing object.

Description

The cos method returns a numeric value between -1 and 1, which represents the cosine of the angle.

Method of

Math

Examples

//Displays the value 6.123031769111886e-017
document.write("The cosine of PI/2 radians is " + Math.cos(Math.PI/2))

//Displays the value -1
document.write("<P>The cosine of PI radians is " + Math.cos(Math.PI))

//Displays the value 1
document.write("<P>The cosine of 0 radians is " + Math.cos(0))

See also

Returns the ASCII encoding of an argument in the ISO Latin-1 character set.

Syntax

escape("string")

string is a non-alphanumeric string in the ISO Latin-1 character set, or a property of an existing object.

Description

The escape function is not a method associated with any object, but is part of the language itself.

The value returned by the escape function is a string of the form "%xx", where xx is the ASCII encoding of a character in the argument. If you pass the escape function an alphanumeric character, the escape function returns the same character.

Examples

The following example returns "%26"

escape("&")

The following example returns "%21%23"

escape("!#")

See also

The eval function evaluates a string and returns a value.

Syntax

eval(string)

Description

The eval function is a built-in JavaScript function. It is not a method associated with any object, but is part of the language itself.

The argument of the eval function is a string. Do not call eval to evaluate an arithmetic expression. JavaScript evaluates arithmetic expressions automatically. If the argument represents an expression, eval evaluates the expression. If the argument represents one or more JavaScript statements, eval performs the statements.

If you construct an arithmetic expression as a string, you can use eval to evaluate it at a later time. For example, suppose you have a variable x. You can postpone evaluation of an expression involving x by assigning the string value of the expression, say "3*x + 2", to a variable, and then calling eval at a later point in your script.

Example

Both of the write statements below display 42. The first evaluates the string "x + y + 1", and the second evaluates the string "42".

var x = 2
var y = 39
var z = "42"
document.write(eval("x + y + 1"), "
" ) 
document.write(eval(z), "
" )

In the following example, the getFieldName(n) function returns the name of the nth form element as a string. The first statement assigns the string value of the third form element to the variable field. The second statement uses eval to display the value of the form element.

var field = getFieldName(3) 
document.write("The field named ", field, " has value of ", eval(field + ".value"))

The following example uses eval to evaluate the string str. This string consists of JavaScript statements that opens an alert dialog box and assigns z a value of 42 if x is five, and assigns zero to z otherwise. When the second statement is executed, eval will cause these statements to be performed, and it will also evaluate the set of statements and return the value that is assigned to z.

var str = "if (x == 5) {alert('z is 42'); z = 42;} else z = 0; "
document.write("
z is ", eval(str))

Returns e^number, where number is the argument, and e is Euler's constant, the base of the natural logarithms.

Syntax

Math.exp(number)

Method of

Math

Examples

//Displays the value 2.718281828459045
document.write("The value of e<SUP>1</SUP> is " + Math.exp(1))

See also

Causes a string to be displayed in fixed-pitch font as if it were in a <TT> tag.

Syntax

stringName.fixed()

stringName is any string or a property of an existing object.

Description

Use the fixed method with the write or writeln methods to format and display a string in a document.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.fixed())

The previous example produces the same output as the following HTML:

<TT>Hello, world</TT>

Returns the greatest integer less than or equal to a number.

Syntax

Math.floor(number)

number is any numeric expression or a property of an existing object.

Method of

Math

Examples

//Displays the value 45
document.write("<P>The floor of 45.95 is " + Math.floor(45.95))

//Displays the value -46
document.write("<P>The floor of -45.95 is " + Math.floor(-45.95))

See also

Gives focus to the specified object.

Syntax

1. passwordName.focus()
2. selectName.focus()
3. textName.focus()
4. textareaName.focus()

passwordName is either the value of the NAME attribute of a password object or an element in the elements array.
selectName is either the value of the NAME attribute of a select object or an element in the elements array.
textName is either the value of the NAME attribute of a text object or an element in the elements array.
textareaName is either the value of the NAME attribute of a textarea object or an element in the elements array.

Description

Use the focus method to navigate to a specific form element and give it focus. You can then either programatically enter a value in the element or let the user enter a value.

Method of

password, select, text, textarea

Examples

In the following example, the checkPassword function confirms that a user has entered a valid password. If the password is not valid, the focus method returns focus to the password object and the select method highlights it so the user can re-enter the password.

function checkPassword(userPass) {
   if (badPassword) {
      alert("Please enter your password again.")
      userPass.focus()
      userPass.select()
   }
}

<INPUT TYPE="password" NAME="userPass">

See also

Causes a string to be displayed in the specified color as if it were in a <FONT COLOR=color> tag.

Syntax

stringName.fontcolor(color)

stringName is any string or a property of an existing object.
color is a string or a property of an existing object, expressing the color as a hexadecimal RGB triplet or as one of the string literals listed in Color Values.

Description

Use the fontcolor method with the write or writeln methods to format and display a string in a document.

If you express color as a hexadecimal RGB triplet, you must use the format rrggbb. For example, the hexadecimal RGB values for salmon are red=FA, green=80, and blue=72, so the RGB triplet for salmon is "FA8072".

The fontcolor method overrides a value set in the fgColor property.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.fontcolor("maroon") +
   " is maroon in this line")
document.write("<P>" + worldString.fontcolor("salmon") +
   " is salmon in this line")
document.write("<P>" + worldString.fontcolor("red") +
   " is red in this line")

document.write("<P>" + worldString.fontcolor("8000") +
   " is maroon in hexadecimal in this line")
document.write("<P>" + worldString.fontcolor("FA8072") +
   " is salmon in hexadecimal in this line")
document.write("<P>" + worldString.fontcolor("FF00") +
   " is red in hexadecimal in this line")

The previous example produces the same output as the following HTML:

<FONT COLOR="maroon">Hello, world</FONT> is maroon in this line
<P><FONT COLOR="salmon">Hello, world</FONT> is salmon in this line
<P><FONT COLOR="red">Hello, world</FONT> is red in this line

<FONT COLOR="8000">Hello, world</FONT> is maroon in hexadecimal in this line
<P><FONT COLOR="FA8072">Hello, world</FONT> is salmon in hexadecimal in this line
<P><FONT COLOR="FF00">Hello, world</FONT> is red in hexadecimal in this line

Causes a string to be displayed in the specified font size as if it were in a <FONTSIZE=size> tag.

Syntax

stringName.fontsize(size)

stringName is any string or a property of an existing object.
size is an integer between one and seven, or a string representing a signed integer between 1 and 7, or a property of an existing object.

Description

Use the fontsize method with the write or writeln methods to format and display a string in a document. When you specify size as an integer, you set the size of stringName to one of the seven defined sizes. When you specify size as a string such as "-2", you adjust the font size of stringName relative to the size set in the <BASEFONT> tag.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.small())
document.write("<P>" + worldString.big())
document.write("<P>" + worldString.fontsize(7))

The previous example produces the same output as the following HTML:

<SMALL>Hello, world</SMALL>
<P><BIG>Hello, world</BIG>
<P><FONTSIZE=7>Hello, world</FONTSIZE>

See also

Loads the next URL in the history list.

Syntax

history.forward()

Description

This method performs the same action as a user choosing the Forward button in the Navigator. The forward method is the same as history.go(1).

Method of

history

Examples

<P><INPUT TYPE="button" VALUE="< Back"
   onClick="history.back()">
<P><INPUT TYPE="button" VALUE="> Forward"
   onClick="history.forward()">

See also

Returns the day of the month for the specified date.

Syntax

dateObjectName.getDate()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getDate is an integer between 1 and 31.

Method of

Date

Examples

The second statement below assigns the value 25 to the variable day, based on the value of the date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
day = Xmas95.getDate()

See also

Returns the day of the week for the specified date.

Syntax

dateObjectName.getDay()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getDay is an integer corresponding to the day of the week: zero for Sunday, one for Monday, two for Tuesday, and so on.

Method of

Date

Examples

The second statement below assigns the value 1 to weekday, based on the value of the date object Xmas95. This is because December 25, 1995 is a Monday.

Xmas95 = new Date("December 25, 1995 23:15:00")
weekday = Xmas95.getDay()

Returns the hour for the specified date.

Syntax

dateObjectName.getHours()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getHours is an integer between 0 and 23.

Method of

Date

Examples

The second statement below assigns the value 23 to the variable hours, based on the value of the date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
hours = Xmas95.getHours()

See also

Returns the minutes in the specified date.

Syntax

dateObjectName.getMinutes()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getMinutes is an integer between 0 and 59.

Method of

Date

Examples

The second statement below assigns the value 15 to the variable minutes, based on the value of the date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
minutes = Xmas95.getMinutes()

See also

Returns the month in the specified date.

Syntax

dateObjectName.getMonth()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getMonth is an integer between zero and eleven. Zero corresponds to January, one to February, and so on.

Method of

Date

Examples

The second statement below assigns the value 11 to the variable month, based on the value of the date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
month = Xmas95.getDate()

See also

Returns the seconds in the current time.

Syntax

dateObjectName.getSeconds()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getSeconds is an integer between 0 and 59.

Method of

Date

Examples

The second statement below assigns the value 30 to the variable secs, based on the value of the date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:30")
secs = Xmas95.getSeconds()

See also

Returns the numeric value corresponding to the time for the specified date.

Syntax

dateObjectName.getTime()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by the getTime method is the number of milliseconds since 1 January 1970 00:00:00. You can use this method to help assign a date and time to another date object.

Method of

Date

Examples

The following example assigns the date value of theBigDay to sameAsBigDay.

theBigDay = new Date("July 1, 1999")
sameAsBigDay = new Date()
sameAsBigDay.setTime(theBigDay.getTime())

See also

Returns the time zone offset in minutes for the current locale.

Syntax

dateObjectName.getTimezoneOffset()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The time zone offset is the difference between local time and GMT. Daylight savings time prevents this value from being a constant.

Method of

Date

Examples

x = new Date()
currentTimeZoneOffsetInHours = x.getTimezoneOffset()/60

Returns the year in the specified date.

Syntax

dateObjectName.getYear()

dateObjectName is either the name of a date object or a property of an existing object.

Description

The value returned by getYear is the year less 1900. For example, if the year is 1976, the value returned is 76.

Method of

Date

Examples

The second statement below assigns the value 95 to the variable year, based on the value of the date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
year = Xmas95.getYear()

See also

Loads a URL from the history list.

Syntax

history.go(delta | "location")

Description

The go method navigates to the location in the history list determined by the argument that you specify. You can interactively display the history list by choosing History from the Window menu. Up to 10 items in the history list are also displayed on the Go menu.

The delta argument is a positive or negative integer. If delta is greater than zero, the go method loads the URL that is that number of entries forward in the history list; otherwise, it loads the URL that is that number of entries backward in the history list. If delta is 0, Navigator reloads the current page.

The location argument is a string. Use location to load the nearest history entry whose URL contains location as a substring. The location to URL matching is case-insensitive. Each section of a URL contains different information. See the location object for a description of the URL components.

Method of

history

Examples

The following button navigates to the nearest history entry that contains the string "home.netscape.com":

<P><INPUT TYPE="button" VALUE="Go"
   onClick="history.go('home.netscape.com')">

The following button navigates to the URL that is three entries backward in the history list:

<P><INPUT TYPE="button" VALUE="Go"
   onClick="history.go(-3)">

See also

Returns the index within the calling string object of the first occurrence of the specified value, starting the search at fromIndex.

Syntax

stringName.indexOf(searchValue, [fromIndex])

stringName is any string or a property of an existing object.
searchValue is a string or a property of an existing object, representing the value to search for.
fromIndex is the location within the calling string to start the search from. It can be any integer from 0 to stringName.length - 1 or a property of an existing object.

Description

Characters in a string are indexed from left to right. The index of the first character is 0, and the index of the last character is stringName.length - 1.

If you do not specify a value for fromIndex, JavaScript assumes 0 by default. If searchValue is not found, JavaScript returns -1.

Method of

string

Examples

var anyString="Brave new world"

//Displays 8
document.write("<P>The index of the first w from the beginning is " +
   anyString.indexOf("w"))
//Displays 10
document.write("<P>The index of the first w from the end is " +
   anyString.lastIndexOf("w"))
//Displays 6
document.write("<P>The index of 'new' from the beginning is " +
   anyString.indexOf("new"))
//Displays 6
document.write("<P>The index of 'new' from the end is " +
   anyString.lastIndexOf("new"))

See also

On Unix platforms, evaluates an argument to determine if it is "NaN" (not a number).

Syntax

isNaN(testValue)

testValue is the value you want to evaluate.

Description

The isNaN function is a built-in JavaScript function. It is not a method associated with any object, but is part of the language itself. isNaN is available on Unix platforms only.

On all platforms except Windows, the parseFloat and parseInt functions return "NaN" when they evaluate a value that is not a number. The "NaN" value is not a number in any radix. You can call the isNaN function to determine if the result of parseFloat or parseInt is "NaN". If "NaN" is passed on to arithmetic operations, the operation results will also be "NaN".

The isNaN function returns true or false.

Examples

The following example evaluates floatValue to determine if it is a number, then calls a procedure accordingly.

floatValue=parseFloat(toFloat)

if isNaN(floatValue) {
   notFloat()
} else {
   isFloat()
}

See also

Causes a string to be italicized as if it were in an <I> tag.

Syntax

stringName.italics()

stringName is any string or a property of an existing object.

Description

Use the italics method with the write or writeln methods to format and display a string in a document.

Method of

string

Examples

var worldString="Hello, world"

document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())

The previous example produces the same output as the following HTML:

<BLINK>Hello, world</BLINK>
<P><B>Hello, world</B>
<P><I>Hello, world</I>
<P><STRIKE>Hello, world</STRIKE>

See also

Returns the index within the calling string object of the last occurrence of the specified value. The calling string is searched backwards, starting at fromIndex.

Syntax

stringName.lastIndexOf(searchValue, [fromIndex])

stringName is any string or a property of an existing object.
searchValue is a string or a property of an existing object, representing the value to search for.
fromIndex is the location within the calling string to start the search from. It can be any integer from 0 to stringName.length - 1 or a property of an existing object.

Description

Characters in a string are indexed from left to right. The index of the first character is 0, and the index of the last character is stringName.length - 1.

If you do not specify a value for fromIndex, JavaScript assumes stringName.length - 1 (the end of the string) by default. If searchValue is not found, JavaScript returns -1.

Method of

string

Examples

var anyString="Brave new world"

//Displays 8
document.write("<P>The index of the first w from the beginning is " +
   anyString.indexOf("w"))
//Displays 10
document.write("<P>The index of the first w from the end is " +
   anyString.lastIndexOf("w"))
//Displays 6
document.write("<P>The index of 'new' from the beginning is " +
   anyString.indexOf("new"))
//Displays 6
document.write("<P>The index of 'new' from the end is " +
   anyString.lastIndexOf("new"))

See also

Creates an HTML hypertext link that jumps to another URL.

Syntax

linkText.link(hrefAttribute)

linkText is any string or a property of an existing object.
hrefAttribute is any string or a property of an existing object.

Description

Use the link method with the write or writeln methods to programatically create and display a hypertext link in a document. Create the link with the link method, then call write or writeln to display the link in a document.

In the syntax, the linkText string represents the literal text that you want the user to see. The hrefAttribute string represents the HREF attribute of the <A> tag, and it should be a valid URL. Each section of a URL contains different information. See the location object for a description of the URL components.

Links created with the link method become elements in the links array. See the link object for information about the links array.

Method of

string

Examples

The following example displays the word "Netscape" as a hypertext link that returns the user to the Netscape home page:

var hotText="Netscape"
var URL="http://www.netscape.com"

document.open()
document.write("Click to return to " + hotText.link(URL))
document.close()

The previous example produces the same output as the following HTML:

Click to return to <A HREF="http://www.netscape.com">Netscape</A>

See also

Returns the natural logarithm (base e) of a number.

Syntax

Math.log(number)

Description

If the value of number is outside the suggested range, the return value is always -1.797693134862316e+308.

Method of

Math

Examples

//Displays the value 2.302585092994046
document.write("The natural log of 10 is " + Math.log(10))

//Displays the value 0
document.write("<P>The natural log of 1 is " + Math.log(1))

//Displays the value -1.797693134862316e+308
//because the argument is out of range
document.write("<P>The natural log of 0 is " + Math.log(0))

See also

Returns the greater of two numbers.

Syntax

max(number1, number2)

Method of

Math

Examples

//Displays the value 20
document.write("The maximum value is " + Math.max(10,20))

//Displays the value -10
document.write("<P>The maximum value is " + Math.max(-10,-20))

See also

Returns the lesser of two numbers.

Syntax

min(number1, number2)

Method of

Math

Examples

//Displays the value 10
document.write("
The minimum value is " + Math.min(10,20))

//Displays the value -20
document.write("<P>The minimum value is " + Math.min(-10,-20))

See also

Opens a stream to collect the output of write or writeln methods.

Syntax

document.open(["mimeType"])

mimeType specifies any of the following document types:

   text/html
   text/plain
   image/gif
   image/jpeg
   image/x-bitmap
   plugIn

Description

The open method opens a stream to collect the output of write or writeln methods. If the mimeType is text or image, the stream is opened to layout; otherwise, the stream is opened to a plug-in. If a document exists in the target window, the open method clears it.

End the stream by using the document.close() method. The close method causes text or images that were sent to layout to display. After using document.close(), issue document.open() again when you want to begin another output stream.

mimeType is an optional argument that specifies the type of document to which you are writing. If you do not specify a mimeType, the open method assumes text/html by default.

Following is a description of mimeType:

Method of

document

Examples

function windowWriter1() {
   var myString = "Hello, world!"
   msgWindow.document.open()
   msgWindow.document.write("<P>" + myString)
   msgWindow.document.close()
}

function probePlugIn(mimeType) {
   var havePlugIn = false
   var tiny = window.open("", "teensy", "width=1,height=1")
   if (tiny != null) {
      if (tiny.document.open(mimeType) != null)
         havePlugIn = true
      tiny.close()
   }
   return havePlugIn
}

var haveShockWavePlugIn = probePlugIn("application/x-director")

See also

Opens a new web browser window.

Syntax

[windowVar = ][window].open("URL", "windowName", ["windowFeatures"])

windowVar is the name of a new window. Use this variable when referring to a window's properties, methods, and containership.
URL specifies the URL to open in the new window. See the location object for a description of the URL components.
windowName is the window name to use in the TARGET attribute of a <FORM> or <A> tag. windowName can contain only alphanumeric or underscore (_) characters.
windowFeatures is a comma-separated list of any of the following options and values:

   toolbar[=yes|no]|[=1|0]
   location[=yes|no]|[=1|0]
   directories[=yes|no]|[=1|0]
   status[=yes|no]|[=1|0]
   menubar[=yes|no]|[=1|0]
   scrollbars[=yes|no]|[=1|0]
   resizable[=yes|no]|[=1|0]
   width=pixels
   height=pixels

You may use any subset of these options. Separate options with a comma. Do not put spaces between the options.

pixels is a positive integer specifying the dimension in pixels.

Description

The open method opens a new web browser window on the client, similar to choosing File|New Web Browser from the menu of the Navigator. The URL argument specifies the URL contained by the new window. If URL is an empty string, a new, empty window is created.

In event handlers, you must specify window.open() instead of simply using open(). Due to the scoping of static objects in JavaScript, a call to open() without specifying an object name is equivalent to document.open().

windowFeatures is an optional, comma-separated list of options for the new window. The boolean windowFeatures options are set to true if they are specified without values, or as yes or 1. For example, open("", "messageWindow", "toolbar") and open("", "messageWindow", "toolbar=1") both set the toolbar option to true. If windowName does not specify an existing window and you do not specify windowFeatures, all boolean windowFeatures are true by default. If you specify any item in windowFeatures, all other Boolean windowFeatures are false unless you explicitly specify them.

Following is a description of the windowFeatures:

Method of

window

Examples

In the following example, the windowOpener function opens a window and uses write methods to display a message:

function windowOpener() {
   msgWindow=window.open("","displayWindow","menubar=yes")
   msgWindow.document.write
      ("<HEAD><TITLE>Message window</TITLE></HEAD>")
   msgWindow.document.write
      ("<CENTER><BIG><B>Hello, world!</B></BIG></CENTER>")
}

The following is an onClick event handler that opens a new client window displaying the content specified in the file sesame.html. The window opens with the specified option settings; all other options are false because they are not specified.

Notice the use of single quotes (') inside the onClick event handler.

See also

Returns the number of milliseconds in a date string since January 1, 1970 00:00:00, local time.

Syntax

Date.parse(dateString)

Description

The parse method takes a date string (such as "Dec 25, 1995"), and returns the number of milliseconds since January 1, 1970 00:00:00 (local time). This function is useful for setting date values based on string values, for example in conjunction with the setTime method and the Date object.

Given a string representing a time, parse returns the time value. It accepts the IETF standard date syntax: "Mon, 25 Dec 1995 13:30:00 GMT". It understands the continental US time zone abbreviations, but for general use, use a time zone offset, for example "Mon, 25 Dec 1995 13:30:00 GMT+0430" (4 hours, 30 minutes west of the Greenwich meridian). If you do not specify a time zone, the local time zone is assumed. GMT and UTC are considered equivalent.

Because the parse function is a static method of Date, you always use it as Date.parse(), rather than as a method of a date object you created.

Method of

Date

Examples

If IPOdate is an existing date object, then

IPOdate.setTime(Date.parse("Aug 9, 1995"))

See also

Parses a string argument and returns a floating point number.

Syntax

parseFloat(string)

string is a string that represents the value you want to parse.

Description

The parseFloat function is a built-in JavaScript function. It is not a method associated with any object, but is part of the language itself.

parseFloat parses its argument, a string, and returns a floating point number. If it encounters a character other than a sign ( + or -), numeral (0-9), a decimal point, or an exponent, then it returns the value up to that point and ignores that character and all succeeding characters.

If the first character cannot be converted to a number, parseFloat returns one of the following values:

For arithmetic purposes, the "NaN" value is not a number in any radix. You can call the isNaN function to determine if the result of parseFloat is "NaN". If "NaN" is passed on to arithmetic operations, the operation results will also be "NaN".

Examples

The following examples all return 3.14:

parseFloat("3.14")
parseFloat("314e-2")
parseFloat("0.0314E+2")
var x = "3.14"
parseFloat(x)

The following example returns "NaN" or 0:

parseFloat("FF2")

See also

Parses a string argument and returns an integer of the specified radix or base.

Syntax

parseInt(string [,radix])

string is a string that represents the value you want to parse.
radix is an integer that represents the radix of the return value.

Description

The parseInt function is a built-in JavaScript function. It is not a method associated with any object, but is part of the language itself.

The parseInt function parses its first argument, a string, and attempts to return an integer of the specified radix (base). For example, a radix of 10 indicates to convert to a decimal number, 8 octal, 16 hexadecimal, and so on. For radixes above 10, the letters of the alphabet indicate numerals greater than 9. For example, for hexadecimal numbers (base 16), A through F are used.

If parseInt encounters a character that is not a numeral in the specified radix, it ignores it and all succeeding characters and returns the integer value parsed up to that point. ParseInt truncates numbers to integer values.

If the radix is not specified or is specified as 0, JavaScript assumes the following:

If the first character cannot be converted to a number, parseFloat returns one of the following values:

For arithmetic purposes, the "NaN" value is not a number in any radix. You can call the isNaN function to determine if the result of parseInt is "NaN". If "NaN" is passed on to arithmetic operations, the operation results will also be "NaN".

Examples

The following examples all return 15:

parseInt("F", 16)
parseInt("17", 8)
parseInt("15", 10)
parseInt(15.99, 10)
parseInt("FXX123", 16)
parseInt("1111", 2)
parseInt("15*3", 10)

The following examples all return "NaN" or 0:

parseInt("Hello", 8)
parseInt("0x7", 10)
parseInt("FFF", 10)

Even though the radix is specified differently, the following examples all return 17 because the input string begins with "0x".

parseInt("0x11", 16)
parseInt("0x11", 0)
parseInt("0x11")

See also

Returns base to the exponent power, that is, base^exponent.

Syntax

pow(base, exponent)

Method of

Math

Examples

//Displays the value 49
document.write("7 to the power of 2 is " + Math.pow(7,2))

//Displays the value 1024
document.write("<P>2 to the power of 10 is " + Math.pow(2,10))

See also

Displays a Prompt dialog box with a message and an input field.

Syntax

prompt(message, [inputDefault])

Description

Use the prompt method to display a dialog box that receives user input. If you do not specify an initial value for inputDefault, the dialog box displays the value <undefined>.

Although prompt is a method of the window object, you do not need to specify a windowReference when you call it. For example, windowReference.prompt() is unnecessary.

Method of

window

Examples

prompt("Enter the number of cookies you want to order:", 12)

See also

Returns a pseudo-random number between zero and one. This method is available on Unix platforms only.

Syntax

Math.random()

Method of

Math

Examples

//Displays a random number between 0 and 1
document.write("The random number is " + Math.random())

Returns the value of a number rounded to the nearest integer.

Syntax

round(number)

Description

If the fractional portion of number is .5 or greater, the argument is rounded to the next highest integer. If the fractional portion of number is less than .5, the argument is rounded to the next lowest integer.

Method of

Math

Examples

//Displays the value 20
document.write("The rounded value is " + Math.round(20.49))

//Displays the value 21
document.write("<P>The rounded value is " + Math.round(20.5))

//Displays the value -20
document.write("<P>The rounded value is " + Math.round(-20.5))

//Displays the value -21
document.write("<P>The rounded value is " + Math.round(-20.51))

Selects the input area of the specified password, text, or textarea object.

Syntax

1. passwordName.select()
2. textName.select()
3. textareaName.select()

passwordName is either the value of the NAME attribute of a password object or an element in the elements array.
textName is either the value of the NAME attribute of a text object or an element in the elements array.
textareaName is either the value of the NAME attribute of a textarea object or an element in the elements array.

Description

Use the select method to highlight the input area of a form element. You can use the select method with the focus method to highlight a field and position the cursor for a user response.

Method of

password, text, textarea

Examples

In the following example, the checkPassword function confirms that a user has entered a valid password. If the password is not valid, the select method highlights the password field and the focus method returns focus to it so the user can re-enter the password.

function checkPassword(userPass) {
   if (badPassword) {
      alert("Please enter your password again.")
      userPass.focus()
      userPass.select()
   }
}

<INPUT TYPE="password" NAME="userPass">

See also

Sets the day of the month for a specified date.

Syntax

dateObjectName.setDate(dayValue)

dateObjectName is either the name of a date object or a property of an existing object.
dayValue is an integer from 1 to 31 or a property of an existing object, representing the day of the month.

Method of

Date

Examples

The second statement below changes the day for theBigDay to the 24th of July from its original value.

theBigDay = new Date("July 27, 1962 23:30:00")
theBigDay.setDate(24)

See also

Sets the hours for a specified date.

Syntax

dateObjectName.setHours(hoursValue)

dateObjectName is either the name of a date object or a property of an existing object.
hoursValue is an integer between 0 and 23 or a property of an existing object, representing the hour.

Method of

Date

Examples

theBigDay.setHours(7)

See also

Sets the minutes for a specified date.

Syntax

dateObjectName.setMinutes(minutesValue)

dateObjectName is either the name of a date object or a property of an existing object.
minutesValue is an integer between 0 and 59 or a property of an existing object, representing the minutes.

Method of

Date

Examples

theBigDay.setMinutes(45)

See also

Sets the month for a specified date.

Syntax

dateObjectName.setMonth(monthValue)

dateObjectName is either the name of a date object or a property of an existing object.
monthValue is an integer between 0 and 11 (representing the months January through Decemeber), or a property of an existing object.

Method of

Date

Examples

theBigDay.setMonth(6)

See also

Sets the seconds for a specified date.

Syntax

dateObjectName.setSeconds(secondsValue)

dateObjectName is either the name of a date object or a property of an existing object.
secondsValue is an integer between 0 and 59 or a property of an existing object.

Method of

Date

Examples

theBigDay.setSeconds(30)

See also

Sets the value of a date object.

Syntax

dateObjectName.setTime(timevalue) 

dateObjectName is either the name of a date object or a property of an existing object.
timevalue is an integer or a property of an existing object, representing the number of milliseconds since the epoch (1 January 1970 00:00:00).

Description

Use the setTime method to help assign a date and time to another date object.

Method of

Date

Examples

theBigDay = new Date("July 1, 1999")
sameAsBigDay = new Date()
sameAsBigDay.setTime(theBigDay.getTime())

See also

Evaluates an expression after a specified number of milliseconds have elapsed.

Syntax

timeoutID=setTimeout(expression, msec)

timeoutID is an identifier that is used only to cancel the evaluation with the clearTimeout method.
expression is a string expression or a property of an existing object.
msec is a numeric value, numeric string, or a property of an existing object in millisecond units.

Description

The setTimeout method evaluates an expression after a specified amount of time. It does not evaluate the expression repeatedly. For example, if a setTimeout method specifies 5 seconds, the expression is evaluated after 5 seconds, not every 5 seconds.

Method of

frame, window

Examples

Example 1. The following example displays an alert message 5 seconds (5,000 milliseconds) after the user clicks a button. If the user clicks the second button before the alert message is displayed, the timeout is cancelled and the alert does not display.