tan method
Returns the tangent of a number.
语法Math.tan(number)
number is a numeric expression representing the size of an angle in radians, or a property of an existing object.
用法
描述
The tan method returns a numeric value which represents the tangent of the angle.
例子//Displays the value 0.9999999999999999
document.write("The tangent of pi/4 radians is " +
Math.tan(Math.PI/4))
//Displays the value 0
document.write("<P>The tangent of 0 radians is " +
Math.tan(0))
相关
acos, asin, atan, cos, sin methods
target property
For form, a string specifying the name of the window that responses go to after a form has been submitted. For link, a string specifying the name of the window that displays the content of a clicked hypertext link.
语法1. formName.target
2. links[index].target
formName is either the name of a form or an element in the forms array.
index is an integer representing a link object.
Property of
描述
The target property initially reflects the TARGET attribute of the <FORM> and <A> tags; however, setting target overrides these attributes.
The target property cannot be assigned the value of a JavaScript expression or variable.
You can set the target property at any time.
Certain values of the target property may require specific values for other form properties. See RFC 1867 for more information.
例子
The following example specifies that responses to the musicInfo form are displayed in the "msgWindow" window: document.musicInfo.target="msgWindow"
相关
For form:
action, encoding, method properties
text object
A text input field on an htm form. A text field lets the user enter a word, phrase, or series of numbers.
语法
To define a text object, use standard htm 语法 with the addition of the onBlur, on Change, onFocus, and onSelect event handlers: <INPUT
TYPE="text"
NAME="textName"
VALUE="textValue"
SIZE=integer
[onBlur="handlerText"]
[onChange="handlerText"]
[onFocus="handlerText"]
[onSelect="handlerText"]>
NAME="textName" specifies the name of the text object. You can access this value using the name property.
VALUE="textValue" specifies the initial value of the text object. You can access this value using the defaultValue property.
SIZE=integer specifies the number of characters the text object can accommodate without scrolling.
To use a text object's properties and methods: 1. textName.propertyName
2. textName.methodName(parameters)
3. formName.elements[index].propertyName
4. formName.elements[index].methodName(parameters)
textName is the value of the NAME attribute of a text 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 text object on a form.
propertyName is one of the properties listed below.
methodName is one of the methods listed below.
Property of
描述
A text object on a form looks as follows:
Last name:
A text object is a form element and must be defined within a <FORM> tag.
text objects can be updated (redrawn) dynamically by setting the value property (this.value).
Properties
defaultValue reflects the VALUE attribute
name reflects the NAME attribute
value reflects the current value of the text object's field
Methods
Event handlers
例子
Example 1. The following example creates a text object that is 25 characters long. The text field appears immediately to the right of the words "Last name:". The text field is blank when the form loads. Last name:
Example 2. The following example creates two text objects on a form. Each object has a default value. The city object has an onFocus event handler that selects all the text in the field when the user tabs to that field. The state object has an onChange event handler that forces the value to upper case.
City:
State:
相关 the 例子 for the onBlur, onChange, onFocus, and onSelect event handlers.
相关
form, password, string, and textarea objects
text property
A string specifying the text that follows an <OPTION> tag in a select object.
语法selectName.options[index].text
selectName is either the value of the NAME attribute of a select object or an element in the elements array.
index is an integer representing an option in a select object.
Property of
options array
描述
The text property initially reflects the text that follows an <OPTION> tag in a select object.
You can set the text property at any time; however, the following effects result:
The value of the property changes.
The text displayed by the option in the select object does not change.
Be careful if you change the text property. If you evaluate the property after you change it, the property contains the new value, not the value that is displayed onscreen.
例子
In the following example, the getChoice() function returns the value of the text property for the selected option. The for loop evaluates every option in the musicType select object. The if statement finds the option that is selected. function getChoice() {
for (var i = 0; i < document.musicForm.musicType.length; i++) {
if (document.musicForm.musicType.options[i].selected == true) {
return document.musicForm.musicType.options[i].text
}
}
return null
}
The previous example assumes that the select object is similar to the following: <SELECT NAME="musicType">
<OPTION SELECTED> R&B
<OPTION> Jazz
<OPTION> Blues
<OPTION> New Age
</SELECT>
textarea object
A multiline input field on an htm form. A textarea field lets the user enter words, phrases, or numbers.
语法
To define a text area, use standard htm 语法 with the addition of the onBlur, onChange, onFocus, and onSelect event handlers: <TEXTAREA
NAME="textareaName"
ROWS="integer"
COLS="integer"
WRAP="off|virtual|physical"
[onBlur="handlerText"]
[onChange="handlerText"]
[onFocus="handlerText"]
[onSelect="handlerText"]>
textToDisplay
</TEXTAREA>
NAME="textareaName" specifies the name of the textarea object. You can access this value using the name property.
ROWS="integer" and COLS="integer" define the physical size of the displayed input field in numbers of characters.
textToDisplay specifies the initial value of the textarea object. A textarea allows only ASCII text, and new lines are respected. You can access this value using the defaultValue property.
The WRAP attribute controls word wrapping inside the TEXTAREA. The value "off" is default and lines are sent exactly as typed. The value "virtual" wraps in the display but are sent exactly as typed. The value "physical" wraps in the display and sends new-lines at the wrap points as if new-lines had been entered.
To use a textarea object's properties and methods: 1. textareaName.propertyName
2. textareaName.methodName(parameters)
3. formName.elements[index].propertyName
4. formName.elements[index].methodName(parameters)
textareaName is the value of the NAME attribute of a textarea 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 textarea object on a form.
propertyName is one of the properties listed below.
methodName is one of the methods listed below.
Property of
描述
A textarea object on a form looks as follows:
Our storage ottoman provides an attractive way to
store lots of CDs and videos--and it's versatile
enough to store other things as well.
It can hold up to 72 CDs under the lid and 20 videos
in the drawer below.
A textarea object is a form element and must be defined within a <FORM> tag.
textarea objects can be updated (redrawn) dynamically by setting the value property (this.value).
To begin a new line in a textarea object, you can use a newline character. This character varies from platform to platform: Unix is \n, Windows is \r\n, and Macintosh is \n. One way to enter a newline character programatically is to test the appVersion property to determine the current platform and set the newline character accordingly. See the appVersion property for an example.
Properties
defaultValue reflects the VALUE attribute
name reflects the NAME attribute
value reflects the current value of the textarea object
Methods
Event handlers
例子
The following example creates a textarea object that is 6 rows long and 55 columns wide. The textarea field appears immediately below the word "描述:". When the form loads, the textarea object contains several lines of data, including one blank line. 描述:
Our storage ottoman provides an attractive way to
store lots of CDs and videos--and it's versatile
enough to store other things as well.
It can hold up to 72 CDs under the lid and 20 videos
in the drawer below.
相关 the 例子 for the onBlur, onChange, onFocus, and onSelect event handlers.
相关
form, password, string, and text objects
title property
A string representing the title of a document.
语法document.title
Property of
描述
The title property is a reflection of the value specified within the <TITLE> and </TITLE> tags. If a document does not have a title, the title property is null.
title is a read-only property.
例子
In the following example, the value of the title property is assigned to a variable called docTitle: var newWindow = window.open("http://www.netscape.com")
var docTitle = newWindow.document.title
toGMTString method
Converts a date to a string, using the Internet GMT conventions.
语法dateObjectName.toGMTString()
dateObjectName is either the name of a date object or a property of an existing object.
用法
描述
The exact format of the value returned by toGMTString varies according to the platform.
例子In the following example, today is a date object: today.toGMTString()
In this example, the toGMTString method converts the date to GMT (UTC) using the operating system's time zone offset and returns a string value that is similar to the following form. The exact format depends on the platform.
Mon, 18 Dec 1995 17:28:35 GMT
相关
toLocaleString method
toLocaleString method
Converts a date to a string, using the current locale's conventions.
语法dateObjectName.toLocaleString()
dateObjectName is either the name of a date object or a property of an existing object.
用法
描述If you are trying to pass a date using toLocaleString, be aware that different locales assemble the string in different ways. Using methods such as getHours, getMinutes, and getSeconds will give more portable results.
例子In the following example, today is a date object: today.toLocaleString()
In this example, toLocaleString returns a string value that is similar to the following form. The exact format depends on the platform.
12/18/95 17:28:35
相关
toGMTString method
toLowerCase method
Returns the calling string value converted to lower case.
语法stringName.toLowerCase()
stringName is any string or a property of an existing object.
用法
描述
The toLowerCase method returns the value of stringName converted to lower case. toLowerCase does not affect the value of stringName itself.
例子
The following 例子 both yield "alphabet". var upperText="ALPHABET"
document.write(upperText.toLowerCase())
"ALPHABET".toLowerCase()
相关
toUpperCase method
top property
The top property is a synonym for the top-most Navigator window, which is a "document window" or "Web Browser window."
语法1. top.propertyName
2. top.methodName
3. top.frameName
4. top.frames[index]
propertyName is defaultStatus, status, or length.
methodName is any method associated with the window object.
frameName and frames[index] are ways to refer to frames.
Property of
描述
The top property refers to the top-most window that contains frames or nested framesets. Use the top property to refer to this ancestor window.
The top property is read-only. The value of the top property is <object objectReference>
where objectReference is an internal reference.
例子
The statement top.close() closes the top-most ancestor window.
The statement top.length specifies the number of frames contained within the top-most ancestor window. When the top-most ancestor is defined as follows, top.length returns 3: <FRAMESET COLS="30%,40%,30%">
<FRAME SRC=child1.htm NAME="childFrame1">
<FRAME SRC=child2.htm NAME="childFrame2">
<FRAME SRC=child3.htm NAME="childFrame3">
</FRAMESET>
The following example sets the background color of a frame called myFrame to red. myFrame is a child of the top-most ancestor window. top.myFrame.document.bgColor="red"
toUpperCase method
Returns the calling string value converted to upper case.
语法stringName.toUpperCase()
stringName is any string or a property of an existing object.
用法
描述
The toUpperCase method returns the value of stringName converted to upper case. toUpperCase does not affect the value of stringName itself.
例子
The following 例子 both yield "ALPHABET". var lowerText="alphabet"
document.write(lowerText.toUpperCase())
"alphabet".toUpperCase()
相关
toLowerCase method
