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javascript手冊-b

摘要: javascript

back method

Loads the previous URL in the history list.

语法

history.back()

用法

history

描述

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).

例子

The following custom buttons perform the same operations as the Navigator Back and Forward buttons:

<input TYPE="button" VALUE="< Back"

   onClick="history.back()">

<input TYPE="button" VALUE="> Forward"

   onClick="history.forward()">

bgColor property

A string specifying the color of the document background.

语法

document.bgColor

Property of

document

描述

The bgColor property is expressed as a hexadecimal RGB triplet or as one of the string literals listed in Color Values. This property is the JavaScript reflection of the BGCOLOR attribute of the <body> tag. The default value of this property is set by the user on the Colors tab of the Preferences dialog box, which is displayed by choosing General Preferences from the Options menu.

You can set the bgColor property at any time.

If you express the 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".

例子

The following example sets the color of the document background to aqua using a string literal:

document.bgColor="aqua"

The following example sets the color of the document background to aqua using a hexadecimal triplet:

document.bgColor="00FFFF"

big method

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

语法

stringName.big()

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

用法

string

描述

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

例子

The following example uses string methods to change the size of a string:

var worldString="Hello, world"

document.write(worldString.small())

document.write("" + worldString.big())

document.write("
" + 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>

blink method

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

语法

stringName.blink()

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

用法

string

描述

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

例子

The following example uses string methods to change the formatting of a string:

var worldString="Hello, world"

document.write(worldString.blink())

document.write("" + worldString.bold())

document.write("
" + worldString.italics())

document.write("
" + 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>

blur method

Removes focus from the specified object.

语法

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.

用法

password, select, text, textarea

描述

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

例子

The following example removes focus from the password element userPass:

userPass.blur()

This example assumes that the password is defined as:

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

bold method

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

语法

stringName.bold()

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

string
描述

Use the bold method with the write or writeln methods to format and display a string in a document.
例子
The following example uses string methods to change the formatting of a string:
var worldString="Hello, world" document.write(worldString.blink()) document.write("
" + worldString.bold()) document.write("
" + worldString.italics()) document.write("
" + worldString.strike())

The previous example produces the same output as the following htm:
Hello, world
Hello, world
Hello, world
Hello, world

See also

blink, italics, strike methods

button object

A pushbutton on an htm form.
语法

To define a button:
<input TYPE="button" NAME="" VALUE="buttonText" [onClick="handlerText"]>
NAME="buttonName" specifies the name of the button object. You can access this value using the name property.
VALUE="buttonText" specifies the label to display on the button face. You can access this value using the value property.
To use a button object's properties and methods:
1. buttonName.propertyName 2. buttonName.methodName(parameters) 3. formName.elements[index].propertyName 4. formName.elements[index].methodName(parameters)
buttonName is the value of the NAME attribute of a button object.
formName is either the value of the NAME attribute of a form object or an element in the forms array.
index is an integer representing a button object on a form.
propertyName is one of the properties listed below.
methodName is one of the methods listed below.
Property of

form
描述

A button object on a form looks as follows: <form>
<input type=button value="Click me"> </form>
A button object is a form element and must be defined within a <form> tag.
The button object is a custom button that you can use to perform an action you define. The button executes the script specified by its onClick event handler.
Properties

name reflects the NAME attribute

value reflects the VALUE attribute
Methods

click
Event handlers

onClick
例子

The following example creates a button named calcButton. The text "Calculate" is displayed on the face of the button. When the button is clicked, the function calcFunction() is called.

See also