PHP determines the ajax request type (HTTP_X_REQUESTED_WITH)-PHP source code

There are many ajax request methods in jquery, but $. ajax, $. get, or $. post, and it can be in json, html, txt, and other formats. In this way, we need to determine whether the HTTP_X_REQUESTED_WITH request sent by php Based on ajax is an ajax request, then, the request in that format is determined based on the $ _ SERVER [HTTP_ACCEPT] Check. There are many ajax request methods in jquery, but $. ajax, $. get, or $. post, and it can be in json, html, txt, and other formats. In this way, we need to determine whether the HTTP_X_REQUESTED_WITH request sent by php Based on ajax is an ajax request, then, based on the $ _ SERVER [\ 'HTTP _ ACCEPT \ '] Check, the request is in that format.

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In php, an ajax request is determined at the header layer. The corresponding result is determined by $ _ SERVER ['HTTP _ X_REQUESTED_WITH.

The Code is as follows:
/** * Whether the current request is an ajax request * * @ Access public * @ Return bool */ Function isAjax () { Return isset ($ _ SERVER ['HTTP _ X_REQUESTED_WITH ']) & strtolower ($ _ SERVER ['HTTP _ X_REQUESTED_WITH']) = 'xmlhttprequest '; }

Generally, $ _ SERVER ['HTTP _ X_REQUESTED_WITH '] Is XMLHttpRequest by default.

Ajax cross-origin can only specify data in the jsonp format. This is not an XMLHttpRequest object. Even if you customize a $ _ SERVER ['HTTP _ X_REQUESTED_WITH '], it is meaningless.

Solution:
Getjson or ajax (jsonp) for cross-origin requests can be determined using the ACCEPT Request Header Format.

PHP end corresponds to $ _ SERVER ['HTTP _ ACCEPT ']

Jsonp requests are generally text/javascript, application/javascript ,*/*

Json request: application/json, text/javascript ,*/*

A simple cross-origin ajax request:

The Code is as follows:
Switch ($ _ SERVER ['HTTP _ ACCEPT ']) { Case 'application/json, text/javascript ,*/*': // JSON format Break; Case 'text/javascript, application/javascript ,*/*': // Javascript or JSONP format Break; Case 'text/html ,*/*': // HTML format Break; Case 'application/xml, text/xml ,*/*': // XML format Break; }