FormData in IE8/9

问题

i have implemented this script for uploading files with ajax, it works perfect in other browsers except for explorer, i noticed that formData is not supported by IE9 and less, are there any alternatives for formData in IE, and i want use clean javascript

    function doObjUploadExplorer(url, lnk_id, file, progress, success, content, frm, div_dlg, start_func){
    var file_input = null,
      frm_data = new FormData(),
      req;

    try {
        //firefox, chrome, safari etc
        req = new XMLHttpRequest();
    }

    catch (e) {
        // Internet Explorer Browsers
        req = new ActiveXObject(\"Microsoft.XMLHTTP\");
    }


if (document.getElementById(file)) {
    file_input = document.getElementById(file);

    for (var i = 0; i < file_input.files.length; ++i) {
        frm_data.append(file, file_input.files[i]);
    }
}

req.upload.addEventListener(\'progress\', function(e) {  //Event called while upload is in progress
    if (progress !== undefined
            && e.lengthComputable) {
        $(\'#\' + progress).html(\'<font>Uploading... \' + Math.round((e.loaded / e.total) * 100) + \'%</font>\');
    }
});

req.upload.addEventListener(\'load\', function(e) {  //Event called when upload is completed
    $(\'#\' + progress).html(\'<font>Retrieving updated data...</font>\');
});

req.upload.addEventListener(\'error\', function(e) {  //Event called when an error is returned by the server
    alert(\'An error has occurred...\');
});

req.addEventListener(\'readystatechange\', function(e) {        
    if (this.readyState === 4) {
        if (this.status === 200) {
            if (content !== undefined) {
                $(\'#\' + content).html(this.response);
            }

            if (success !== undefined) {
                showChkMark(success);
            }
        } else {
            console.log(\'Server replied with HTTP status: \' + this.status);
        }


        if (progress !== undefined) {
            $(\'#\' + progress).hide();
        }

        if (div_dlg !== undefined) {
            $(\'#\' + div_dlg).dialog(\'close\');
        }

        $(\'#\' + file)
        .attr(\'disabled\', false)
        .val(\'\');
    }
});

if (progress !== undefined) {
    $(\'#\' + progress).show();
}

$(\'#\' + file).attr(\'disabled\', true);
url += (
        url.indexOf(\'?\') === -1
        ? \'?\'
        : \'&\'
    );
url += \'lnk_id=\' + lnk_id + \'&file=\' + file;
req.open(\'POST\', url);
req.setRequestHeader(\'Cache-Control\', \'no-cache\');

if (start_func !== undefined) {
    start_func.apply();
    setTimeout(function() {
        req.send(frm_data);
    }, 500);
} else {
    req.send(frm_data);
}}

回答1:

FormData in IE is only supported from IE10, after doing some research the best solution for this (my opinion) would be using ajaxForm: http://malsup.com/jquery/form/ works perfect in IE8/9, not sure about IE7

来源：https://stackoverflow.com/questions/15475215/formdata-in-ie8-9