Implementation and Application of js ajax

XMLHttpRequestObject is used to transfer data between the browser and the server.

ajax simple case to access the text, in server environments:

// Create ajax objects, incompatible versions IE low
 var XHR = new new the XMLHttpRequest () ;
 // onreadstatechange specify a callback function, dynamically monitor the communication state (the readyState),
 . XHR the onreadystatechange = function () {
      // communication state 4 when indicating the browser has been fully accepted data server, which has failed to accept this
 IF (XHR. the readyState === . 4 ) {
          // http status indicates a status code 200 indicating a normal
 IF (XHR. status === 200 is ) {
              Document . Write (XHR. the responseText ) ;
 } the else {
              Document .  
                        Write (XHR. the statusText ) ;
          } 
     } 
 } ;
  . XHR the onerror = function (E) {
      Console . error (XHR. the statusText ) ;
  } ;
 // the GET mode, the path for the path under local environment, true for asynchronous request, to false synchronous
 XHR. Open ( 'the GET' , './1.txt' , to true ) ;
 . XHR Send ( null ) ;  
 

result

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