PHP basics of AJAX Interview

AJAX content basis

　　　The basic operating principle of Ajax

　　　　　　Ajax basic concepts: by a small amount of data exchanged with the server in the background, Ajax can be used to implement asynchronous page updates

　　　　　　Ajax works: XMLHttpRequest is the foundation of Ajax

　　　　　　　　　　　　   XMLHttpRequest for exchanging data with the server in the background,

　　　　　　XMLHttpRequest Object Request

　　　　　　　　　　open(method，url，async)

　　　　　　　　　　send(string);

　　　　　　XMLHttpRequest object response

　　　　　　　　　　

　　　jQuery's Ajax operations

　　　　responseText

　　　　responseXML

　　　　onreadystatechange

　　　　readyState: 0 (uninitialized parent seeking), 1 (server connection is established), 2 (request has been received), 3 (request processing), 4 (request has been completed, and the response is ready)

　　　　status：200    400

　　　Commonly used methods: $ (ele) .load () $ .ajax () $ .get () $ .post () $ getJSON () $ .getScript ()