AJAX错误，未显示所有信息

Question

var xmlHttp = createXmlHttpRequestObject();

function createXmlHttpRequestObject() {
    var xmlHttp;

    if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();

    } else {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");

    }

    return xmlHttp;
}

function process() {
    if (xmlHttp) {
        xmlHttp.open("GET", "bacon.txt", true);
        xmlHttp.onreadystatechange = handleServerResponse();
        xmlHttp.send(null);
    }
}

function handleServerResponse() {

    theD = document.getElementById('theD');

    if (xmlHttp.readyState == 1) {
        theD.innerHTML += "Status 1:server connection established";
    }

    if (xmlHttp.readyState == 2) {
        theD.innerHTML += "Status 2:done";
    }

    if (xmlHttp.readyState == 3) {
        theD.innerHTML += "Status 3:done again";

    }

    if (xmlHttp.readyState == 4) {
        if (xmlHttp.status = 200) {

            text = xmlHttp.responseText;
            theD.innerHTML += "Status 4:request done";
            theD.innerHTML += text
        }
    }
}

我只获得"server connection established"作为输出。