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Today I'll tell you what the status of ajax requests are. The content of the article is good. Now I would like to share it with you. Friends who feel in need can understand it. I hope it will be helpful to you. Let's read it along with the editor's ideas.

The status of the ajax request: 1, "uninitialized", indicating that the send () method has not been called; 2, "loading", indicating that the send () method has been called and sending the request; 3, "loading completed"; 4, "interaction", indicating that the response content is being parsed; 5, "complete", indicating that the response content parsing is complete and can be called on the client side.

The operating environment of this tutorial: windows7 system, javascript1.8.5 version, Dell G3 computer.

Native ajax request is written:

Var http = new XMLHttpRequest (); http.open ('get','./package.json'); http.onreadystatechange = function () {if (http.readyState = = 4 & & http.status = = 200) {var result = JSON.parse (http.responseText); console.log (result.name)}}; http.send ()

5 states of ajax request (readyState)

0-(uninitialized) the send () method has not been called yet

1-(load) has called the send () method and is sending the request

2-(load completed) the send () method has been executed and all the response contents have been received.

3-(interactive) parsing response content

4-(complete) the parsing of the response content is complete and can be called on the client side.

ReadyState status description

(0) uninitialized

This phase confirms that the XMLHttpRequest object is created and does not call the open () method to prepare for uninitialization. A value of less than 0 indicates that the object already exists, otherwise the browser will report an error-the object does not exist.

(1) load

In this stage, the xml (standardization is getting closer and closer) HttpRequest object is initialized, that is, the open () method is called, and the object state is set according to the parameter (method,url,true). And call the send () method to start sending the request to the server. A value of 1 indicates that a request is being sent to the server.

(2) loading completed

This phase receives the response data from the server. However, what is obtained is only the original data of the server response, which can not be used directly on the client side. A value of 2 indicates that all response data has been received. And prepare for the next stage of data parsing.

(3) interaction

This phase parses the received server-side response data. That is, according to the MIME type returned by the server-side response header, the data is converted into a format that can be accessed through responseBody, responseText, or responsexml (standardization is getting closer and closer) attributes, in preparation for client-side call. Status 3 indicates that the data is being parsed.

(4) complete

This phase confirms that all the data has been parsed to the format available to the client, and the parsing is complete. A value of 4 means that the data has been parsed and can be obtained through the corresponding properties of the xml (standardization is getting closer and closer) HttpRequest object.

What is ajaxajax is a technology that can update part of the web page without reloading the whole web page. It can update the web page asynchronously by exchanging a small amount of data with the server in the background.

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