JavaScript·JavaScript的方法 -- 追寻梦想＞编程乐园

Examples

In the following example, the testValue function checks the name entered by a user in the text element 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 of an application to enter a valid value.

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

You can call the testValue function in the onBlur event handler of a form's text element, as shown in the following example:

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

anchor method

Causes the calling string object to be a named anchor by surrounding it with HTML anchor tags, <A NAME=...> </A>.

Syntax

string.anchor(name)

The argument name can be any string.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

asin method

Returns the arc sine (in radians) of its argument.

Syntax

asin(arg)

Applies to

Examples

xxx Examples to be supplied.

assign method

Sets location.href so you don't have to type ".href" complements toString().

Syntax

assign()

Description

Do not call the assign method. It exists so you can use 'location=...' instead of 'location.href=...'. xxx Description to be supplied.

Applies to

location

Examples

xxx Examples to be supplied.

atan method

Returns the arc tangent (in radians) of its argument.

Syntax

atan(arg)

Applies to

Examples

xxx Examples to be supplied.

back method

Loads the previous URL in the history list.

Syntax

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 go(-1).

Applies to

history

Examples

xxx Examples to be supplied.

big method

Causes the calling string object to be displayed in big font by surrounding it with HTML big font tags, <BIG> and </BIG>.

Syntax

big()

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

blink method

Causes the calling string object to blink by surrounding it with HTML blink tags, <BLINK> ... </BLINK>.

Syntax

blink()

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

blur method

For password, text, and textArea, removes focus to the object.

Syntax

blur()

Description

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

Applies to

password, text, textArea

Examples

xxx Examples to be supplied.

bold method

Causes the calling string object to be displayed as bold by surrounding it with HTML bold tags, <B> ... </B>.

Syntax

bold()

NOTE: For Beta4, use B() for this method.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

ceil method

Returns the least integer greater than or equal to its argument.

Syntax

ceil(arg)

Applies to

Examples

xxx Examples to be supplied.

charAt method

Returns the character at the specified index.

Syntax

charAt(index)

index is any integer from 0 to string.length() - 1.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

clear method

Clears the window.

Syntax

clear()

Description

xxx Description to be supplied.

Applies to

document

Examples

xxx Examples to be supplied.

clearTimeout method

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

xxx Description to be supplied. Applies to

Examples

xxx Examples to be supplied.

click method

Simulates a mouse click on the calling form element.

Syntax

click()

Description

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

For button, reset, and submit, xxx.

For a radioButton, selects a radio button.

For a checkbox, checks the check box and sets its value to on.

For a selection, sets its value.

Applies to

button, checkbox, radioButton, reset, selection, submit

Examples

xxx Examples to be supplied.

close method

For document and window, closes the window. xxx Not yet implemented in Beta 4.

Syntax

close()

Description

Document description to be supplied.

The close method closes the current window.

Applies to

document, window

Examples

Any of the following examples close the current window:

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

confirm method

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

Syntax

confirm("message")

The argument message is any string.

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 decison. The confirm method returns true if the user chooses OK and false if the user chooses Cancel.

Applies to

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()
   }
}

You can call the confirmCleanUp function in the onClick event handler of a form's pushbutton, as shown in the following example:

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

cos method

Returns the cosine of its argument. The argument is in radians.

Syntax

cos(arg)

Applies to

Examples

xxx Examples to be supplied.

eval function

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

Syntax

eval(expression)

Description

The eval function takes a JavaScript arthimetic expression as its argument and returns the value of the argument as a number.

Example

Both of the uses of eval in the following example assign the value 42 to the variable result.

x = 6
result = eval((3+3)*7)
result = eval(x*7)

exp method

Returns e to the power of its argument, i.e. e^x, where x is the argument, and e is Euler's constant, the base of the natural logarithms.

Syntax

exp(arg)

Applies to

Examples

xxx Examples to be supplied.

fixed method

Causes the calling string object to be displayed in fixed-pitch font in HTML by surrounding it with typewriter text tags, <fixed> ... </fixed>.

Syntax

fixed()

NOTE: For Beta4, use TT() for this method.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

floor method

Returns the greatest integer less than or equal to its argument.

Syntax

floor(arg)

Applies to

Examples

xxx Examples to be supplied.

focus method

For password, text, and textArea, gives focus to the object.

Syntax

focus()

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.

Applies to

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 focus method returns focus to the password field 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()
   }
}

This example assumes that the password is defined as:

<INPUT TYPE=password NAME=userPass>

fontcolor method

Causes the calling string object to be displayed in the specified color by surrounding it with HTML font color tags, <FONTCOLOR=color> ... </FONTCOLOR>.

Syntax

fontcolor(color)

The argument to the method, color, must be a string containing a hashmark (#) followed by a triplet of hexadecimal number pairs. These three pairs represent the red, green, and blue values for the desired color, respectively.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

fontsize method

Causes the calling string object to be displayed in the specified font size by surrounding it with HTML font size tags, <FONTSIZE=size> ... </FONTSIZE>.

Syntax

fontsize(size)

The argument to the method, size, must be an integer between one and seven.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

forward method

Loads the next URL in the history list.

Syntax

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 go(1).

Applies to

history

Examples

xxx Examples to be supplied.

getDate method

Syntax

dateObj.getDate()

where dateObj is a date object.

Description

Returns the day of the month for the date object, an integer between 1 and 31.

Applies to

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()

getDay method

Syntax

dateObj.getDay()

where dateObj is a date object.

Description

Returns the day of the week for the date object, an integer corresponding to the day of the week: zero for Sunday, one for Monday, two for Tuesday, and so on.

Applies to

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()

getHours method

Syntax

dateObj.getHours()

where dateObj is a date object.

Description

Returns the hour for the date object, an integer between 0 and 23.

Applies to

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()

getMinutes method

Syntax

dateObjgetMinute()

where dateObj is a date object.

Description

Returns the minutes in the date object, an integer between 0 and 59.

Applies to

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()

getMonth method

Syntax

dateObj.getMonth()

where dateObj is a date object.

Description

Returns the month in the date object, an integer between zero and eleven. Zero corresponds to January, one to Februrary, and so on.

Applies to

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()

getSeconds method

Syntax

dateObj.getSeconds()

where dateObj is a date object.

Description

Returns the seconds in the current time, an integer between 0 and 59.

Applies to

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()

getTime method

Syntax

dateObj.getTime()

where dateObj is a date object.

Description

Returns the numeric value for the date object. This number is the number of milliseconds since the epoch (1 January 1970 00:00:00) You can use this method to help assign a date and time to another date object.

Applies to

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())

getTimezoneOffset method

Syntax

dateObj.getTimezoneOffset()

where dateObj is a date object.

Description

Return the time zone offset in minutes for the current locale, i.e. the difference between the local time and GMT. This value would be a constant except for daylight savings time.

Applies to

Examples

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

getYear method

Syntax

getyear()

Description

Returns the year in the date object, less 1900.

Applies to

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()

go method

The argument delta is an integer. If delta is greater than zero, then it 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.

The argument string is a string. Go to the newest history entry whose title or URL contains string as a substring; substring matching is case-insensitive.

Syntax

go(delta | "string")

Description

xxx Description to be supplied.

Applies to

history

Examples

xxx Examples to be supplied.

indexOf method

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

Syntax

indexOf(character, [fromIndex])

character is the character to search for.
fromIndex is the location within the calling string to start the search from, any integer from 0 to string.length() - 1.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

italics method

Causes the calling string object to be italicized by surrounding it with HTML italics tags, <I> ... </I>.

Syntax

italics()

NOTE: For Beta4, use I() for this method.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

lastIndexOf method

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

Syntax

indexOf(character, [fromIndex])

character is the character to search for.
fromIndex is the location within the calling string to start the search from, any integer from 0 to string.length() - 1.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

link method

Causes the calling string object to be a hyperlink by surrounding it with HTML hyperlink tags, <A HREF=...> </A>.

Syntax

link(location)

The argument to the method, location, should be a valid URL.

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

log method

Returns the natural logarithm (base e) of its argument.

Syntax

log(arg)

Applies to

Examples

xxx Examples to be supplied.

max method

Returns the greater of its two arguments.

Syntax

max(arg1, arg2)

Applies to

Examples

xxx Examples to be supplied.

Syntax

min(arg1, arg2)

Applies to

Examples

xxx Examples to be supplied.

open method

For the window object, opens a new web browser window. xxx For the document object, description to be supplied.

Syntax

The first form of the syntax is for the document object; the second form is for window.

1. document.open("MIME type")
2. window.open("URL", "windowName", ["windowFeatures"])

URL specifies the URL to open in the new window.
windowName specifies a name for the window object being opened.
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]
   copyhistory[=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.

NOTE: In event handlers, you must specify window.open() unless you want to call document.open() because of the scoping of static objects in JavaScript.

Description for window

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.

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.

Following is a description of the windowFeatures:

toolbar creates the standard Navigator toolbar, with buttons such as "Back" and "Forward", if true

location creates a Location entry field, if true

directories creates the standard Navigator directory buttons, such as "What's New" and "What's Cool", if true

status creates the status bar at the bottom of the window, if true

menubar creates the menu at the top of the window, if true

scrollbars creates horizontal and vertical scrollbars when the document grows larger than the window dimensions, if true

resizable allows a user to resize the window, if true

copyhistory gives the new window the same session history as the current window, if true

width specifies the width of the window in pixels

height specifies the height of the window in pixels

Description for document

Description to be supplied.

Applies to

document, window

Examples

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

function windowOpener() {
   msgWindow=open("","Display window","toolbar=no,directories=no,menubar=no");
   msgWindow.document.write("<HEAD><TITLE>Message window</TITLE>");
   msgWindow.document.write("<CENTER><BIG><B>Hello, world!</B>");
}

The following is an onClick event handler that opens a new client window displaying the content specified in the file sesame.html. It opens it with the specified option settings and names the corresponding window object newWin.

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

parse method

Syntax

Date.parse(date string)

Description

The parse function 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.

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.

The parse function is a static method of Date. That means that you always use it as Date.parse(), rather than as a method of a date object you created.

Applies to

Examples

If IPOdate is an existing date object, then

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

pow method

Returns arg1 to the arg2 power, i.e. arg1^arg2.

Syntax

pow(arg1, arg2)

Applies to

Examples

xxx Examples to be supplied.

prompt method

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

Syntax

prompt(message, input default)

Description

Use the prompt method to display a dialog box that takes user input. The arguments, message and input default are JavaScript values to be displayed as the message and the default value in the input field, respectively.

Applies to

Examples

prompt("Enter the number of doughnuts you want:", 12)

random method

Returns a pseudo-random number between zero and one. xxx NYI.

Syntax

xxx To be supplied.

Applies to

Examples

xxx Examples to be supplied.

round method

Returns its argument, rounded to the nearest integer. In other words, if its argument is n.5 or greater (where n is an integer), returns n+1, otherwise returns n.

Syntax

round(arg)

Applies to

Examples

xxx Examples to be supplied.

select method

For password, text, and textArea, selects the input area of the object.

Syntax

select()

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.

Applies to

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 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()
   }
}

This example assumes that the password is defined as:

<INPUT TYPE=password NAME=userPass>

setDate method

Syntax

dateObj.setDate(day)

where dateObj is a date object.

Description

Sets the day of the month for the date object. The argument is an integer from 1 to 31.

Applies to

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")
Xmas95.setDate(24)

setHours method

Syntax

dateObj.setHours(hours

where dateObj is a date object.

Description

Sets the hours in the current time. The argument is an integer between 0 and 23.

Applies to

Examples

theBigDay.setHours(7)

setMinutes method

Syntax

dateObj.setMinutes(minutes)

where dateObj is a date object.

Description

Sets the minutes in the current time. The argument is an integer between 0 and 59.

Applies to

Examples

theBigDay.setMinutes(45)

setMonth method

Syntax

dateObj.setMonth(month)

where dateObj is a date object.

Description

Sets the month in the current date. The argument is an integer between 0 and 11.

Applies to

Examples

theBigDay.setMonth(6)

setSeconds method

Syntax

dateObj.setSeconds(seconds)

where dateObj is a date object.

Description

Sets the seconds in the current time. The argument is an integer between 0 and 59.

Applies to

Examples

theBigDay.setSeconds(30)

setTime method

Syntax

dateObj.setTime(timevalue)

where dateObj is a date object.

Description

Sets the value of the date object. This argument is the number of milliseconds since the epoch (1 January 1970 00:00:00) You can use this method to help assign a date and time to another date object.

Applies to

Examples

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

setTimeout method

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

Syntax

timeoutID=setTimeout(expression, msec)

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

Description

xxx Description to be supplied. Applies to

Examples

xxx Examples to be supplied.

setYear method

Syntax

dateObj.setYear(year)

where dateObj is a date object.

Description

Sets the year in the current date. Takes as its argument an integer greater than 1900.

Applies to

Examples

theBigDay.setYear(96)

sin method

Returns the sine of its argument. The argument is in radians.

Syntax

sin(arg)

Applies to

Examples

xxx Examples to be supplied.

small method

Causes the calling string object to be displayed in small font by surrounding it with HTML small font tags, <SMALL>....

Syntax

small()

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

sqrt method

Returns the square root of its argument.

Syntax

sqrt(arg)

Applies to

Examples

xxx Examples to be supplied.

strike method

Causes the calling string object to be displayed as struck out text, by surrounding it with HTML strikeout tags, <STRIKE> ... </STRIKE>.

Syntax

strike()

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

sub method

Causes the calling string object to be displayed as a subscript by surrounding it with HTML subscript tags, <SUB> ... </SUB>.

Syntax

sub()

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

sup method

submit method

Submits the form.

Syntax

submit()

Description

xxx Description to be supplied.

Applies to

form

Examples

xxx Examples to be supplied.

substring method

The substring method returns a subset of a string object. If a < b, then it returns the subset starting at character a and ending before character b, considering the first character of the string to be character zero (0). If a > b, then it returns the subset starting at character b and ending at character a. If a = b, then it returns the empty string.

Syntax

substring(a, b)

Description

xxx Description to be supplied.

Applies to

Examples

If string x is "netscape" then x.substring(0,3) or x.substring(3,0) returns "net", and x.substring(4,7) or x.substring(7,4) returns "cap".

sup method

Causes the calling string object to be displayed as a superscript by surrounding it with HTML superscript tags, <SUP> ... </SUP>.

Syntax

sup()

Description

xxx Description to be supplied.

Applies to

Examples

xxx Examples to be supplied.

tan method

Returns the tangent of its argument. The argument is in radians.

Syntax

tan(arg)

Applies to

Examples

xxx Examples to be supplied.

toGMTString method

Syntax

dateObj.toGMTString()

where dateObj is a date object.

Description

Converts a date to a String, using the Internet GMT conventions.

Applies to

Examples

today.toGMTString()

If today is a date object, then toGMTString would convert the date to GMT (UTC) using the operating system's time zone offset, and return a string value in the following form:
Mon, 18 Dec 1995 17:28:35 GMT

toLocaleString method

Syntax

dateObj.toLocaleString()

where dateObj is a date object.

Description

Converts a date to a String, using the locale conventions.

Applies to

Examples

today.toLocaleString()

If today is a date object, then toLocaleString will return a string value in the following form:
12/18/95 17:28:35

toLowerCase method

The toLowerCase method of string objects converts the string to all upper case.

Syntax

toLowerCase()

Description

xxx Description to be supplied.

Applies to

Examples

For example, "ALPHABET".toLowerCase yields "alphabet".

toString method

For location, returns location.href, so you can use location as a string without typing ".href". For Date, converts a date to a string.

Syntax

toString()

Description

xxx Description to be supplied.

Applies to

location, Date methods

Examples

Here is an example of using toString with a date object, assuming theBigDay is a date object:

theBigDay.toString()

More Examples to be supplied.

toUpperCase method

The toUpperCase method of string objects converts the string to all upper case.

Syntax

toUpperCase()

Description

xxx Description to be supplied.

Applies to

Examples

For example, "alphabet".toUpperCase yields "ALPHABET".

UTC method

Syntax

Date.UTC(year, month, mday [, hrs] [, min] [, sec])

Description

UTC takes comma-delimited date parameters and returns the number of milliseconds since January 1, 1970 00:00:00, Universal Coordinated Time (GMT). The arameters are:

year - a year after 1900
month - a month between 0-11
date - day of the month between 1-31
hrs - hours between 0-23
min - minutes between 0-59
sec - seconds between 0-59

UTC is a static method of Date. That means that you always use it as Date.UTC(), rather than as a method of a date object you created.

Applies to