Returns the tangent of a number.
Math.tan(number)
number is a numeric expression representing the size of an angle in radians, or a property of an existing object.
The tan method returns a numeric value which represents the tangent of the angle.
//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))
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.
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.
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.
The following example specifies that responses to the musicInfo form are displayed in the "msgWindow" window:
document.musicInfo.target="msgWindow"
For form:
A text input field on an HTML form. A text field lets the user enter a word, phrase, or series of numbers.
To define a text object, use standard HTML syntax 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.
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.
A text object on a form looks as follows:
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).
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.
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.
See also the examples for the onBlur, onChange, onFocus, and onSelect event handlers.
A string specifying the text that follows an <OPTION> tag in a select object.
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.
options array
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:
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.
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>
A multiline input field on an HTML form. A textarea field lets the user enter words, phrases, or numbers.
To define a text area, use standard HTML syntax 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.
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.
A textarea object on a form looks as follows:
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.
The following example creates a textarea object that is 6 rows long and 55 columns wide. The textarea field appears immediately below the word "Description:". When the form loads, the textarea object contains several lines of data, including one blank line.
See also the examples for the onBlur, onChange, onFocus, and onSelect event handlers.
A string representing the title of a document.
document.title
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.
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
Converts a date to a string, using the Internet GMT conventions.
dateObjectName.toGMTString()
dateObjectName is either the name of a date object or a property of an existing object.
The exact format of the value returned by toGMTString varies according to the platform.
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
Converts a date to a string, using the current locale's conventions.
dateObjectName.toLocaleString()
dateObjectName is either the name of a date object or a property of an existing 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
Returns the calling string value converted to lower case.
stringName.toLowerCase()
stringName is any string or a property of an existing object.
The toLowerCase method returns the value of stringName converted to lower case. toLowerCase does not affect the value of stringName itself.
The following examples both yield "alphabet".
var upperText="ALPHABET" document.write(upperText.toLowerCase()) "ALPHABET".toLowerCase()
The top property is a synonym for the top-most Navigator window, which is a "document window" or "Web Browser window."
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.
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.
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"
Returns the calling string value converted to upper case.
stringName.toUpperCase()
stringName is any string or a property of an existing object.
The toUpperCase method returns the value of stringName converted to upper case. toUpperCase does not affect the value of stringName itself.
The following examples both yield "ALPHABET".
var lowerText="alphabet" document.write(lowerText.toUpperCase()) "alphabet".toUpperCase()
Returns the ASCII string for the specified value.
unescape("string")
string is a string or a property of an existing object, containing characters in either of the following forms:
The unescape function is not a method associated with any object, but is part of the language itself.
The string returned by the unescape function is a series of characters in the ISO Latin-1 character set.
The following example returns "&"
unescape("%26")
The following example returns "!#"
unescape("%21%23")
A string representing the value of the user-agent header sent in the HTTP protocol from client to server.
navigator.userAgent
Servers use the value sent in the user-agent header to identify the client.
userAgent is a read-only property.
The following example displays userAgent information for the Navigator:
document.write("The value of navigator.userAgent is " + navigator.userAgent)
For Navigator 2.0, this displays the following:
The value of navigator.userAgent is Mozilla/2.0 (Win16; I)
Returns the number of milliseconds in a date object since January 1, 1970 00:00:00, Universal Coordinated Time (GMT).
Date.UTC(year, month, day [, hrs] [, min] [, sec])
year is a year after 1900.
month is a month between 0-11.
date is a day of the month between 1-31.
hrs is hours between 0-23.
min is minutes between 0-59.
sec is seconds between 0-59.
UTC takes comma-delimited date parameters and returns the number of milliseconds since January 1, 1970 00:00:00, Universal Coordinated Time (GMT).
Because UTC is a static method of Date, you always use it as Date.UTC(), rather than as a method of a date object you created.
The following statement creates a date object using GMT instead of local time:
gmtDate = new Date(Date.UTC(96, 11, 1, 0, 0, 0))
A string that is related to the VALUE attribute of its object.
1. objectName.value 2. radioName[index].value 3. selectName.options.[index].value
objectName is either the value of the NAME attribute of a hidden, password, text, textarea, button, reset, submit or checkbox object or an element in the elements array.
radioName is the value of the NAME attribute of a radio object.
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 a radio button in a radio object or an option in a select object.
The value property differs for every object.
You can set the value property at any time. The display of the text and textarea objects updates immediately when you set the value property.
The value property is a string that initially reflects the VALUE attribute. This string is represented by asterisks in the password object field. The value of this property changes when a user or a program modifies the field, but the value is always displayed as asterisks.
If you programatically set the value property and then evaluate it, JavaScript returns the current value. If a user interactively modifies the value in the password field, you cannot evaluate it accurately for security reasons.
When a VALUE attribute is specified in HTML, the value property is a string that reflects it. This string is displayed on the face of the button.
When a VALUE attribute is not specified in HTML, the value property differs for each object:
These strings are displayed on the faces of the buttons.
value is a read-only property.
Do not confuse the value property with the name property. The name property is not displayed onscreen; it is used to reference the objects programatically.
The value property is a string that initially reflects the VALUE attribute. The value of this property can change when a program modifies it. The value property is not displayed onscreen, but is returned to the server if the option is selected.
You can set the value property at any time.
Do not confuse the value property with the selection state of the select object or the text that is displayed as an option. The selected and selectedIndex properties determine which options are selected, and the defaultSelected property determines the default selection state. The text that is displayed in each option is specified by its text property.
When a VALUE attribute is specified in HTML, the value property is a string that reflects it. When a VALUE attribute is not specified in HTML, the value property is a string that evaluates to "on". The value property is not displayed onscreen, but is returned to the server if the radio button or checkbox is selected.
You can set the value property at any time.
Do not confuse the value property with the selection state of the object or the text that is displayed next to each checkbox and radio button. The checked property determines the selection state of the object, and the defaultChecked property determines the default selection state. The text that is displayed is specified following the <INPUT TYPE="checkbox"> or the <INPUT TYPE="radio"> tag.
The following function evaluates the value property of a group of buttons and displays it in the msgWindow window:
function valueGetter() { var msgWindow=window.open("") msgWindow.document.write("submitButton.value is " + document.valueTest.submitButton.value + "<BR>") msgWindow.document.write("resetButton.value is " + document.valueTest.resetButton.value + "<BR>") msgWindow.document.write("helpButton.value is " + document.valueTest.helpButton.value + "<BR>") msgWindow.document.close() }
This example displays the following values:
Query Submit Reset Help
The previous example assumes the buttons have been defined as follows
<INPUT TYPE="submit" NAME="submitButton"> <INPUT TYPE="reset" NAME="resetButton"> <INPUT TYPE="button" NAME="helpButton" VALUE="Help">
The following function evaluates the value property of a group of radio buttons and displays it in the msgWindow window:
function valueGetter() { var msgWindow=window.open("") for (var i = 0; i < document.valueTest.radioObj.length; i++) { msgWindow.document.write ("The value of radioObj[" + i + "] is " + document.valueTest.radioObj[i].value +"<BR>") } msgWindow.document.close() }
This example displays the following values:
on on on on
The previous example assumes the buttons have been defined as follows
<BR><INPUT TYPE="radio" NAME="radioObj">R&B <BR><INPUT TYPE="radio" NAME="radioObj" CHECKED>Soul <BR><INPUT TYPE="radio" NAME="radioObj">Rock and Roll <BR><INPUT TYPE="radio" NAME="radioObj">Blues
For hidden, password, text, and textarea:
For button, reset, and submit:
For options array:
For checkbox and radio:
A string specifying the color of visited links.
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