1.XMLHttpRequest:

1.XMLHttpRequest:

GET:

var client = new XMLHttpRequest();
client.onreadystatechange = handler;
client.open("GET", "unicorn.xml");
client.send();

function handler() {
  if(this.readyState == this.DONE) {
    if(this.status == 200 &&
       this.responseXML != null && this.responseXML.getElementById('test').textContent) {
      // success!
      processData(this.responseXML.getElementById('test').textContent);
      return;
    }
    // something went wrong
    processData(null);
  }
}

If you just want to log a message to the server:

function log(message) {
  var client = new XMLHttpRequest();
  client.open("POST", "/log");
  client.setRequestHeader("Content-Type", "text/plain;charset=UTF-8");
  client.send(message);
}

Or if you want to check the status of a document on the server:

function fetchStatus(address) {
  var client = new XMLHttpRequest();
  client.onreadystatechange = function() {
    // in case of network errors this might not give reliable results
    if(this.readyState == this.DONE)
      returnStatus(this.status);
  }
  client.open("HEAD", address);
  client.send();
}

来自为知笔记(Wiz)Time=2012-12-26 11:19:59