javascript手冊-s2

setTimeout method

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

语法

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.

方法

frame, window

描述

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.

例子

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 canceled and the alert does not display.

Example 2. The following example displays the current time in a text object. The showtime() function, which is called recursively, uses the setTimeout method update the time every second.

相关

setYear method

Sets the year for a specified date.

语法

dateObjectName.setYear(yearValue)

dateObjectName is either the name of a date object or a property of an existing object.
yearValue is an integer greater than 1900 or a property of an existing object.

方法

Date

例子

theBigDay.setYear(96)

相关

sin method

Returns the sine of a number.

语法

Math.sin(number)

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

方法

Math

描述

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

例子

//Displays the value 1document.write(The sine of pi/2 radians is  +   Math.sin(Math.PI/2))//Displays the value 1.224606353822377e-016document.write(<P>The sine of pi radians is  +   Math.sin(Math.PI))//Displays the value 0document.write(<P>The sine of 0 radians is  +   Math.sin(0))

相关

small method

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

语法

stringName.small()

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

方法

string

描述

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

例子

var worldString=Hello, worlddocument.write(worldString.small())document.write(<P> + worldString.big())document.write(<P> + worldString.fontsize(7))

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

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

相关

sqrt method

Returns the square root of a number.

语法

Math.sqrt(number)

方法

Math

描述

If the value of number is outside the suggested range, the return value is always 0.

例子

//Displays the value 3document.write(The square root of 9 is  + Math.sqrt(9))//Displays the value 1.414213562373095document.write(<P>The square root of 2 is  + Math.sqrt(2))//Displays the value 0 because the argument is out of rangedocument.write(<P>The square root of -1 is  + Math.sqrt(-1))

SQRT1_2 property

The square root of one-half; equivalently, one over the square root of two, approximately 0.707.

语法

Math.SQRT1_2

Property of

Math

描述

Because SQRT1_2 is a constant, it is a read-only property of Math.

例子

The following example displays 1 over the square root of 2:

document.write(1 over the square root of 2 is  + Math.SQRT1_2)

相关

SQRT2 property

The square root of two, approximately 1.414.

语法

Math.SQRT2

Property of

Math

描述

Because SQRT2 is a constant, it is a read-only property of Math.

例子

The following example displays the square root of 2:

document.write(The square root of 2 is  + Math.SQRT2)

相关

status property

Specifies a priority or transient message in the status bar at the bottom of the window, such as the message that appears when a mouseOver event occurs over an anchor.

语法

windowReference.status

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

Property of

window

描述

Do not confuse the status property with the defaultStatus property. The defaultStatus property reflects the default message displayed in the status bar.

You can set the status property at any time. You must return true if you want to set the status property in the onMouseOver event handler.

例子

Suppose you have created a JavaScript function called pickRandomURL() that lets you select a URL at random. You can use the onClick event handler of an anchor to specify a value for the HREF attribute of the anchor dynamically, and the onMouseOver event handler to specify a custom message for the window in the status property:

In the above example, the status property of the window is assigned to the windows self property, as self.status. As this example shows, you must return true to set the status property in the onMouseOver event handler.

相关

strike method

Causes a string to be displayed as struck out text as if it were in a <STRIKE> tag.

语法

stringName.strike()

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

方法

string

描述

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

例子

var worldString=Hello, worlddocument.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 htm:

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

相关

string object

A series of characters.

语法

To use a string object:

1. stringName.propertyName2. stringName.methodName(parameters)

Property of

描述

The string object is a built-in JavaScript object.

A string can be represented as a literal enclosed by single or double quotes; for example, Netscape or Netscape.

Properties

Methods

Event handlers

例子

The following statement creates a string variable.

相关

sub method

Causes a string to be displayed as a subscript as if it were in a <SUB> tag.

语法

stringName.sub()

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

方法

string

描述

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

例子

var superText=superscriptvar subText=subscriptdocument.write(This is what a  + superText.sup() +  looks like.)document.write(<P>This is what a  + subText.sub() +  looks like.)

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

This is what a <SUP>superscript</SUP> looks like.<P>This is what a <SUB>subscript</SUB> looks like.

相关

sup method

submit method

Submits a form.

语法

formName.submit()

formName is the name of any form or an element in the forms array.

方法

form

描述

The submit method submits the specified form. It performs the same action as a submit button.

Use the submit method to send data back to an http server. The submit method returns the data using either get or post, as specified in the method property.

例子

The following example submits a form called musicChoice:

document.musicChoice.submit()

If musicChoice is the first form created, you also can submit it as follows:

document.forms[0].submit()

相关 the example for the form object.

相关

submit object

A submit button on an htm form. A submit button causes a form to be submitted.

语法

To define a submit button, use standard htm 语法 with the addition of the onClick event handler:

<INPUT   TYPE=submit   NAME=submitName   VALUE=buttonText   [onClick=handlerText]>

To use a submit objects properties and methods:

1. submitName.propertyName2. submitName.methodName(parameters)3. formName.elements[index].propertyName4. formName.elements[index].methodName(parameters)

Property of

描述

A submit object on a form looks as follows:

A submit object is a form element and must be defined within a <FORM> tag.

Clicking a submit button submits a form to the URL spec