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JavaScript window and input and output of JavaScript tutorial

黄舟Original: 2016-12-22 15:37:271427browse

JavaScript is an object-based scripting programming language, so its input and output are completed through objects. The input can be accomplished through the Window object, and the output can be accomplished through the methods of the document object.

Window and input and output

Please see the following example:

<html>
<head>
<meta charset="utf-8">
<script languaga="JavaScript">var test = window.prompt("请输入数据:");document.write(test+"JavaScript 输入输出的例子");
</script>
</head>
</html>

where window.prompt() is a method of the window object. Its basic function is to display a message with "OK" and "OK" on the screen when the Web page is loaded. "Cancel" dialog box, allowing you to export data. document.writle is a method of the document object, and its basic function is to realize the output display of the Web page.

1. Window object

This object includes many useful properties, methods and event drivers. Programmers can use these objects to control various aspects of the browser window display, such as dialog boxes, frames, etc. The following points should be noted when using:

a. This object corresponds to the two identifiers of 9c5594a5fc8d2e506f1a8147102c836b and 0185c77847b632968e9815dc59319b1a in the HTML document;

b, onload and onunload are all window object attributes;

c. Window objects can be referenced directly in JavaScript scripts. For example:

window.alert("Window object input method")

You can directly use the following format:

alert("Window object input method")

2. Event-driven window object

Window object There are mainly onload events for loading Web documents and onunload events for unloading. Used to start and stop updating the document when the document is loading and stopping loading.

3. Methods of the window object

The methods of the window object are mainly used to provide information or input data and create a new window.

Create a new window open()

Use the window.open (parameter list) method to create a new window. The parameter table provides the main characteristics of the window and the naming of documents and windows.

Dialog with OK button

alert() method can create a dialog with OK button.

Dialog with OK and Cancel buttons

confirm() method provides the programmer with a dialog with two buttons.

Dialog box with input information

prompt() method allows users to enter information in the dialog box and use default values. Its basic format is prompt("prompt information", default value).

4. Attributes in the window object

The attributes in the window object are mainly used to reference various windows and frames that exist in the browser. Its main attributes are as follows:

a, frames Correct The number of frames in the document.

Frames (frames) play a very useful role in realizing the separation operation of a window. Please pay attention to the following points when using it: The frames attribute is referenced through the order of the HTML mark c7bb6e6cc0efaf2f6df8ad8a086e2c75, which contains the contents of a window. of all frames. The frame itself is a type of window, inheriting all properties and methods of the window object.

b, Parent indicates the parent window of the current window or frame.

c, defaultstatus: Default status, its value is displayed in the status bar of the window.

d, status: Contains the current information in the frame in the document window.

e, top: Includes the window used to implement all subordinate windows.

f, window. refers to the current window.

g, self: refers to the current window.

5. Output stream and document object

In the JavaScript document object, an output stream is provided for displaying, closing, eliminating, and opening HTML pages.

a. Create a new document open() method.

Use document.open() to create a new window or open the document in the specified command window. Since the window object is the loaded parent object, we do not need to add the Window object when calling its properties or methods. Example Window.Open() is the same as Open().

The basic format of opening a window:

Window .open("URL","Window Name","Window Properties"]

The window attribute parameter is a string list item separated by commas, which specifies the relevant Properties of the newly created window.

b, write(), writeln() output display.

This method is mainly used to display output information on the Web page. In actual use, please pay attention to the following points: writeln(). The only difference from write() is that a change character is added at the end. In order to display the output information normally, the e03b848252eb9375d56be284e690e873 95d483d68176e55f9a932a16e502f614 mark must be specified to tell the editor the output document type. Determined by the valid legal text type in the browser.

c. Close the document stream close().

When implementing multiple document objects, you must use close() to close one object before opening another document. Object.

d, clear document content clear().

Use this method to clear the content of the opened document.

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