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摘要: javascript
Returns the least integer greater than or equal to a number.
Math.ceil(number)
number is any numeric expression or a property of an existing object.
Math
//Displays the value 46 document.write("The ceil of 45.95 is " + Math.ceil(45.95)) //Displays the value -45 document.write("The ceil of -45.95 is " + Math.ceil(-45.95))
Returns the character at the specified index.
stringName.charAt(index)
stringName is any string or a property of an existing object.
index is any integer from 0 to stringName.length - 1, or a property of an existing object.
string
Characters in a string are indexed from left to right. The index of the first character is 0, and the index of the last character is stringName.length - 1. If the index you supply is out of range, JavaScript returns an empty string.
var anyString="Brave new world" document.write("The character at index 0 is " + anyString.charAt(0)) document.write("The character at index 1 is " + anyString.charAt(1)) document.write("The character at index 2 is " + anyString.charAt(2)) document.write("The character at index 3 is " + anyString.charAt(3)) document.write("The character at index 4 is " + anyString.charAt(4))
A checkbox on an htm form. A checkbox is a toggle switch that lets the user set a value on or off.
To define a checkbox, use standard htm 语法 with the addition of the onClick event handler:
<input TYPE="checkbox" NAME="" VALUE="checkboxValue" [CHECKED] [onClick="handlerText"]> textToDisplayNAME="checkboxName" specifies the name of the checkbox object. You can access this value using the name property.
To use a checkbox object's properties and methods:
1. checkboxName.propertyName 2. checkboxName.methodName(parameters) 3. formName.elements[index].propertyName 4. formName.elements[index].methodName(parameters)checkboxName is the value of the NAME attribute of a checkbox object.
A checkbox object on a form looks as follows: <form>
<input CHECKED type=checkbox> Overnight delivery </form>
A checkbox object is a form element and must be defined within a <form> tag.
Use the checked property to specify whether the checkbox is currently checked. Use the defaultChecked property to specify whether the checkbox is checked when the form is loaded.
Example 1. The following example displays a group of four checkboxes that all appear checked by default.
Example 2. The following example contains a form with three text boxes and one checkbox. The checkbox lets the user choose whether the text fields are converted to upper case. Each text field has an onChange event handler that converts the field value to upper case if the checkbox is checked. The checkbox has an onClick event handler that converts all fields to upper case when the user checks the checkbox.
<input TYPE="checkBox" NAME="convertUpper" onClick="if (this.checked) {convertAllFields()}" > Convert fields to upper case </form> </body>
A Boolean value specifying the selection state of a checkbox object or radio button.
1. checkboxName.checked 2. radioName[index].checked
checkboxName is either the value of the NAME attribute of a checkbox object or an element in the elements array.
radioName is the value of the NAME attribute of a radio object.
index is an integer representing a radio button in a radio object.
checkbox, radio
If a checkbox or radio button is selected, the value of its checked property is true; otherwise, it is false.
You can set the checked property at any time. The display of the checkbox or radio button updates immediately when you set the checked property.
The following example examines an array of radio buttons called musicType on the musicForm form to determine which button is selected. The VALUE attribute of the selected button is assigned to the checkedButton variable.
function stateChecker() { var checkedButton = "" for (var i in document.musicForm.musicType) { if (document.musicForm.musicType[i].checked=="1") { checkedButton=document.musicForm.musicType[i].value } } }
Clears the document in a window.
document.clear()
document
The clear method empties the content of a window, regardless of how the content of the window has been painted.
When the following function is called, the clear method empties the contents of the msgWindow window:
function windowCleaner() { msgWindow.document.clear() msgWindow.document.close() }
Cancels a timeout that was set with the setTimeout method.
clearTimeout(timeoutID)
timeoutID is a timeout setting that was returned by a previous call to the setTimeout method.
frame, window
See the 描述 for the setTimeout method.
See the 例子 for the setTimeout method.
Simulates a mouse click on the calling form element.
1. buttonName.click() 2. radioName[index].click()
3. checkboxName.click()
buttonName is either the value of the NAME attribute of a button, reset, or submit object or an element in the elements array.
radioName is the value of the NAME attribute of a radio object or an element in the elements array.
index is an integer representing a radio button in a radio object.
checkboxName is either the value of the NAME attribute of a checkbox object or an element in the elements array.
button, checkbox, radio, reset, submit
The effect of the click method varies according to the calling element:
The following example toggles the selection status of the first radio button in the musicType radio object on the musicForm form:
document.musicForm.musicType[0].click()
The following example toggles the selection status of the newAge checkbox on the musicForm form:
document.musicForm.newAge.click()
Closes an output stream and forces data sent to layout to display.
document.close()
document
The close method closes a stream opened with the document.open() method. If the stream was opened to layout, the close method forces the content of the stream to display. Font style tags, such as and The close method also stops the "meteor shower" in the Netscape icon and displays "Document: Done" in the status bar.
")
msgWindow.document.close()
}
Closes the specified window.
windowReference is a valid way of referring to a window, as described in the window object.
window
The close method closes the specified window. If you call close without specifying a windowReference, JavaScript closes the current window.
In event handlers, you must specify window.close() instead of simply using close(). Due to the scoping of static objects in JavaScript, a call to close() without specifying an object name is equivalent to document.close().
Any of the following 例子 close the current window: The following example closes the messageWin window: This example assumes that the window was opened in a manner similar to the following: Displays a Confirm dialog box with the specified message and OK and Cancel buttons.
confirm("message")
message is any string or a property of an existing object.
window
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 decision. The confirm method returns true if the user chooses OK and false if the user chooses Cancel.
Although confirm is a 用法 the window object, you do not need to specify a windowReference when you call it. For example, windowReference.confirm() is unnecessary.
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. String value of a cookie, which is a small piece of information stored by the Navigator in the cookies.txt file.
document
Use string methods such as substring, charAt, indexOf, and lastIndexOf to determine the value stored in the cookie. See the Netscape cookie specification for a complete specification of the cookie 语法.
You can set the cookie property at any time.
The following function uses the cookie property to record a reminder for users of an application. The "expires=" component sets an expiration date for the cookie, so it persists beyond the current browser session. The format of the date must be This is the same date format as returned by Date.toGMTString, except:
For example, a valid cookie expiration date is: When the user loads the page that contains this function, another function uses indexOf("@") and indexOf("=") to determine the date and time stored in the cookie.
Returns the cosine of a number.
number is a numeric expression representing the size of an angle in radians, or a property of an existing object.
Math
The cos method returns a numeric value between -1 and 1, which represents the cosine of the angle.
The cosine of PI radians is " + Math.cos(Math.PI))
//Displays the value 1
document.write(" The cosine of 0 radians is " + Math.cos(0))
例子
The following function calls document.close() to close a stream that was opened with document.open(). The document.close() method forces the content of the stream to display in the window. function windowWriter1() {
var myString = "Hello, world!"
msgWindow.document.open()
msgWindow.document.write(myString + "
See also
close method (window object)
语法
windowReference.close()
用法
描述
例子
window.close()
self.close()
close()
messageWin.close()
messageWin=window.open("")
See also
confirm method
语法
用法
描述
例子
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()">
See also
cookie property
语法
document.cookie
Property of
描述
例子
Wdy, DD-Mon-YY HH:MM:SS GMT
where Wdy is the full name of the day of the week, DD is an integer representation of the day of the month, Mon is the month, YY is the last two digits of the year, and HH, MM, and SS are two-digit representations of hours, minutes, and seconds, respectively.
expires=Wednesday, 09-Nov-99 23:12:40 GMT function RecordReminder(time, expression) {
// Record a cookie of the form "@
See also
cos method
语法
Math.cos(number)
用法
描述
例子
//Displays the value 6.123031769111886e-017
document.write("The cosine of PI/2 radians is " + Math.cos(Math.PI/2))
//Displays the value -1
document.write("
See also