<script type="text/javascript">
 var oMyWorker = new Worker("myTask.js"); 
 oMyWorker.onmessage = function(oEvent) { 
  alert("Worker said: " + oEvent.data);
 };
 oMyWorker.postMessage("Hello");
</script>
myFile.txt ( XMLHttpRequest对象同步请求的文件):
Hello World!! 

 self.onmessage = function (oEvent) {
 if (oEvent.data === "Hello") {
var oReq = new XMLHttpRequest();
oReq.open("GET", "myFile.txt", false); // 同步请求
oReq.send(null);
self.postMessage(oReq.responseText);
 }
}; 

 window.onbeforeunload = function () {
 var oReq = new XMLHttpRequest();
 oReq.open("GET", "logout.php?nick=" + escape(myName), false); // 同步请求
 oReq.send(null);
 if (oReq.responseText.trim() !== "已退出"); { // "已退出"是返回的数据
return "退出失败,您想手动执行退出吗?";
 }
}; 

 function loadFile (sURL, timeout, fCallback /*, 传入参数1, 传入参数2, 等 */) {
 var aPassArgs = Array.prototype.slice.call(arguments, 3), oReq = new XMLHttpRequest();
 oReq.ontimeout = function() {
console.log("请求超时.");
 }
 oReq.onreadystatechange = function() {
if (oReq.readyState === 4) { 
 if (oReq.status === 200) {
  fCallback.apply(oReq, aPassArgs);
 } else {
  console.log("Error", oReq.statusText);
 }
}
 };
 oReq.open("GET", sURL, true);
 oReq.timeout = timeout;
 oReq.send(null);
} 

 function showMessage (sMsg) {
 alert(sMsg + this.responseText);
}
loadFile("message.txt", 200, showMessage, "New message!\\n"); 

 function switchXHRState() {
 switch (this.readyState) {
case 0: console.log("还没调用open()方法."); break;
case 1: console.log("还没调用send()方法."); break;
case 2: console.log("已经调用send()方法,响应头和响应状态已经返回."); break;
case 3: console.log("下载中,已经得到部分响应实体."); break;
case 4: console.log("请求完成!"); this.callback.apply(this, this.arguments);
 }
};
function loadFile (sURL, fCallback /*, 传入参数1, 传入参数2, 等 */) {
 var oReq = new XMLHttpRequest();
 oReq.callback = fCallback;
 oReq.arguments = Array.prototype.slice.call(arguments, 2);
 oReq.onreadystatechange = switchXHRState;
 oReq.open("GET", sURL, true);
 oReq.send(null);
} 

function switchXHRState(fCallback, aArguments) {
 switch (this.readyState) {
case 0: console.log("还没调用open()方法."); break;
case 1: console.log("还没调用send()方法."); break;
case 2: console.log("已经调用send()方法,响应头和响应状态已经返回."); break;
case 3: console.log("下载中,已经得到部分响应实体."); break;
case 4: console.log("请求完成!"); fCallback.apply(this, aArguments);
 }
};
function loadFile (sURL, fCallback /*, 传入参数1, 传入参数2, 等 */) {
 var oReq = new XMLHttpRequest();
 oReq.onreadystatechange = switchXHRState.bind(oReq, fCallback, Array.prototype.slice.call(arguments, 2));
 oReq.open("GET", sURL, true);
 oReq.send(null);
}