相关疑难解决方法(0)

我试图发送一些表单而不重新加载页面,我试图理解引擎盖下的细节,因此不使用任何JavaScript库:

var http = createRequestObject();
function createRequestObject() {
    var objAjax;
    if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari
        objAjax=new XMLHttpRequest();
    }
    else
    {// code for IE6, IE5
        objAjax=new ActiveXObject("Microsoft.XMLHTTP");
    }
    return objAjax;
}

function display_progress() { ... }    

function upload_file() {
    var request = 'UploaderServlet';
    http.open('post', request);
    http.onreadystatechange = display_progress;
    http.send(null); // HERE PROBABLY THE DATA SHOULD BE SENT
}

<form enctype="multipart/form-data" id="upload_form" name="upload_form" method="POST" action="UploaderServlet" onsubmit="upload_file(); return false;" target="upload_target">
Choose a file <br />  
<input name="file" size="27" …