Window object in JavaScript_Basic knowledge

The Window object in JavaScript
is the largest object in JavaScript. It describes a browser window. Generally, when you want to reference its properties and methods, you do not need to use the form "window.xxx", but use "xxx" directly. A frame page is also a window.

Window window object has the following attributes:



name The name of the window, consisting of the connection () or frame page () that opened it or a certain Determined by the open() method (see below) called by a window. Generally we will not use this attribute.

status refers to the content displayed in the "status bar" at the bottom of the window. By assigning a value to status, you can change the display of the status bar.

opener Usage: window.opener; returns the window object that opens this window. Note: What is returned is a window object. If the window is not opened by another window, this property returns null in Netscape and "undefined" in IE. undefined is equal to null to a certain extent. Note: undefined is not a JavaScript constant. If you try to use "undefined", it will really return "undefined".

self refers to the window itself, and the object it returns is exactly the same as the window object. The most commonly used is "self.close()", placed in the tag: "Close window ".

parent returns the frame page object to which the window belongs.

top returns the frame page object that occupies the top of the entire browser window.

history historical object, see below.

location address object, see below.

document document object, see below.



Window object has the following methods:
The first method is open() to open a window.
Usage:
open(, , );

Description:



: Description of what is opened Which web page is open in the window. If left blank (''), no web page will be opened.

: Describes the name of the opened window (window.name). You can use built-in names such as '_top' and '_blank'. The name here is the same as the "target" attribute in "".

: Describes the appearance of the opened window. If you only need to open a normal window, leave the string blank (''). If you want to specify the appearance, write one or more parameters in the string, separated by commas.


Example: Open a 400 x 100 clean window:
open('','_blank','width=400,height=100,menubar=no,toolbar=no,
location=no,directories=no,status=no, scrollbars=yes,resizable=yes')

open() parameters



top=# The number of pixels from the top of the window to the top of the screen

left=# The number of pixels from the left end of the window to the left end of the screen

width=# The width of the window

height=# The height of the window

menubar=... Whether the window has a menu, the value is yes or no

toolbar=... Whether the window has a toolbar, the value is yes or no

location= ... Does the window have an address bar? The value is yes or no.

directories=... Does the window have a connection area? The value is yes or no.

scrollbars=... Does the window have a connection area? Scroll bar, value yes or no

status=... Whether the window has a status bar, value yes or no

resizable=... Whether the window will be resized, value yes or no


Note: The open() method has a return value, and what is returned is the window object it opens. For example,
var newWindow = open('','_blank');

Assign a new window to the "newWindow" variable, and then you can control the window through the "newWindow" variable.

close() closes an open window.
Usage:
window.close()

or
self.close()

The main function is to close this window;
.close( ): Close the specified window. Note that if the window has a status bar, after calling this method, the browser will warn: "The webpage is trying to close the window, do you want to close it?" and then wait for the user to choose whether; if there is no status bar, calling this method will directly close the window.
In addition, the Window object also has the following methods



blur() to remove the focus from the window and make the window an "inactive window".

focus() causes the window to gain focus and become the "active window".However, in Windows 98, this method can only make the window's title bar and the corresponding button on the taskbar flash, prompting the user that the window is trying to gain focus.

scrollTo() Usage: [.]scrollTo(x, y); Scroll the window so that the document scrolls from the (x, y) point counting from the upper left corner to the upper left corner of the window.

scrollBy() usage: [.]scrollBy(deltaX, deltaY); causes the window to scroll right by deltaX pixels and down by deltaY pixels. A negative value scrolls in the opposite direction.

resizeTo() usage: [.]resizeTo(width, height); causes the window to be resized to width width pixels and height height pixels.

resizeBy() Usage: [.]resizeBy(deltaWidth, deltaHeight); Make the window resize, increase the width by deltaWidth pixels, and increase the height by deltaHeight pixels. If it takes a negative value, it decreases.

alert() usage: alert(); pops up a dialog box containing only the "OK" button and displays the content of . The entire document reading and script running will be suspended until The user presses "OK".

confirm() Usage: confirm(); pops up a dialog box containing "OK" and "Cancel" buttons, displays the content of , requires the user to make a choice, and reads the entire document Fetching and script execution will be paused. Returns a true value if the user pressed "OK" and a false value if "Cancel" was pressed.

prompt() Usage: prompt([, ]); pops up a dialog box containing "Confirm", "Cancel" and a text box, display the content of , and ask the user Enter some data in the text box, and the entire document reading and script execution will be suspended. If the user presses "Confirm", the existing content in the text box is returned. If the user presses "Cancel", a null value is returned. If is specified, the text box will have a default value.



Window object has the following events:
window.onload; occurs when all documents have been downloaded. The completion of all downloads means that not only the HTML files, but also all the included images, plug-ins, controls, applets, etc. have been downloaded. This event is a window event, but when specifying the event handler in HTML, we write it in the tag.
window.onunload; occurs when the user exits the document (or closes the window, or goes to another page). Like onload, if you want to write it in HTML, write it in the tag.



window.onresize; occurs when the window is resized.

window.onblur; occurs when the window loses focus.

window.onfocus; occurs when the window gets focus.

window.onerror; occurs when an error occurs. Its event handler is usually called an "Error Handler" and is used to handle errors. As mentioned above, to ignore all errors, use:
function ignoreError() {
return true;
}
window.onerror = ignoreError;