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This article mainly explains "what is the new writing method of fetch_ajax request in XMLHttpRequest". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the new writing method of fetch_ajax request in XMLHttpRequest"?

The fetch () function is an Promise-based mechanism for programmatically generating Web requests in browsers. The project is a polyfill that implements a subset of the standard Fetch specification and is sufficient to provide a viable alternative to most uses of XMLHttpRequest in traditional fetch Web applications.

Fetch installation method:

The de facto standard, which does not exist in the ES6 specification, is implemented based on Promise. At present, there are still some problems in the compatibility of Promise in the project. If fetch is applied in the project, es6-promise and fetch need to be introduced.

Install whatwg-fetch (like ajax, the new way to get data, support promise syntax) to get data.

Npminstallwhatwg-fetch--save

Or

Bowerinstallfetch.

Current location: lazy people build sites > javascript tutorials > usage of fetch (fetch new generation ajax request scheme)

Basic Fetch request

Let's first compare an example of using XMLHttpRequest with an example of using the fetch method. The example makes a request to the server, gets the response, and parses it using JSON.

XMLHttpRequest

A XMLHttpRequest needs to set up two event callback functions, one to be called if the data is successful and the other to be called when it fails to get the data, as well as an open () method call and a send () method call.

FunctionreqListener () {

Vardata=JSON.parse (this.responseText)

Console.log (data)

}

FunctionreqError (err) {

Console.log ("Fetch error:" + err)

}

VaroReq=newXMLHttpRequest ()

OReq.onload=reqListener

OReq.onerror=reqError

OReq.open ("get", "/ students.json", true)

OReq.send ()

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