var request;

if(windoe.XMLHtprequest){

　　request=new XMLHttprequest();

}else{

　　request = new ActiveXObject();

}

function success(text) {

    var textarea = document.getElementById('test-ie-response-text');

    textarea.value = text;

}

function fail(code) {

    var textarea = document.getElementById('test-ie-response-text');

    textarea.value = 'Error code: ' + code;

}

var request = new ActiveXObject('Microsoft.XMLHTTP'); // 新建Microsoft.XMLHTTP对象

request.onreadystatechange = function () { // 状态发生变化时，函数被回调

    if (request.readyState === 4) { // 成功完成

        // 判断响应结果:

        if (request.status === 200) {

            // 成功，通过responseText拿到响应的文本:

            return success(request.responseText);

        } else {

            // 失败，根据响应码判断失败原因:

            return fail(request.status);

        }

    } else {

        // HTTP请求还在继续...

    }

}

// 发送请求:

request.open('GET', '/api/categories');

request.send();

alert('请求已发送，请等待响应...');