Question

我使用此代码上传文件，此代码有一个进度条。此代码的问题在于，在上传文件后，它在进度条上达到100％之后，它永远不会将我发送到“upload.php”。（这不是我的代码）。

代码：

// get form data for POSTing
//var vFD = document.getElementById('upload_form').getFormData(); // for FF3
var vFD = new FormData(document.getElementById('upload_form')); 

// create XMLHttpRequest object, adding few event listeners, and POSTing our data
var oXHR = new XMLHttpRequest();        
oXHR.upload.addEventListener('progress', uploadProgress, false);
oXHR.addEventListener('load', uploadFinish, false);
oXHR.addEventListener('error', uploadError, false);
oXHR.addEventListener('abort', uploadAbort, false);
oXHR.open('POST', 'upload.php');
oXHR.send(vFD);

整个剧本

// common variables
var iBytesUploaded = 0;
var iBytesTotal = 0;
var iPreviousBytesLoaded = 0;
var iMaxFilesize = 1048576; // 1MB
var oTimer = 0;
var sResultFileSize = '';

var uploadingcanceld = "حدث خطأ أثناء تحميل الملف";


function secondsToTime(secs) { // we will use this function to convert seconds in normal time format
    var hr = Math.floor(secs / 3600);
    var min = Math.floor((secs - (hr * 3600))/60);
    var sec = Math.floor(secs - (hr * 3600) -  (min * 60));

    if (hr < 10) {hr = "0" + hr; }
    if (min < 10) {min = "0" + min;}
    if (sec < 10) {sec = "0" + sec;}
    if (hr) {hr = "00";}
    return hr + ':' + min + ':' + sec;
};

function bytesToSize(bytes) {
    var sizes = ['Bytes', 'KB', 'MB'];
    if (bytes == 0) return 'n/a';
    var i = parseInt(Math.floor(Math.log(bytes) / Math.log(1024)));
    return (bytes / Math.pow(1024, i)).toFixed(1) + ' ' + sizes[i];
};

function fileSelected() {

    // hide different warnings
    document.getElementById('upload_response').style.display = 'none';
    document.getElementById('error').style.display = 'none';
    document.getElementById('error2').style.display = 'none';
    document.getElementById('abort').style.display = 'none';
    document.getElementById('warnsize').style.display = 'none';

    // get selected file element
    var oFile = document.getElementById('ufile').files[0];

    // filter for image files
    var rFilter = /^(image\/bmp|image\/gif|image\/jpeg|image\/png|image\/tiff)$/i;
    if (! rFilter.test(oFile.type)) {
        document.getElementById('error').style.display = 'block';
        return;
    }

    // little test for filesize
    if (oFile.size > iMaxFilesize) {
        document.getElementById('warnsize').style.display = 'block';
        return;
    }

    // get preview element
    var oImage = document.getElementById('preview');

    // prepare HTML5 FileReader
    var oReader = new FileReader();
        oReader.onload = function(e){

        // e.target.result contains the DataURL which we will use as a source of the image
        oImage.src = e.target.result;

        oImage.onload = function () { // binding onload event

            // we are going to display some custom image information here
            sResultFileSize = bytesToSize(oFile.size);
            document.getElementById('fileinfo').style.display = 'block';
            document.getElementById('filename').innerHTML = 'Name: ' + oFile.name;
            document.getElementById('filesize').innerHTML = 'Size: ' + sResultFileSize;
            document.getElementById('filetype').innerHTML = 'Type: ' + oFile.type;
            document.getElementById('filedim').innerHTML = 'Dimension: ' + oImage.naturalWidth + ' x ' + oImage.naturalHeight;
        };
    };

    // read selected file as DataURL
    oReader.readAsDataURL(oFile);
}

function startUploading() {
    // cleanup all temp states
    iPreviousBytesLoaded = 0;
    $("#upload").animate({height:'75px'},350);
    $("#loadingborders").fadeIn(1500);
    $("#progress_percent").fadeIn(1500);
    $("#upload_button").fadeOut(100);
    $("#ufile").fadeOut(100);
    document.getElementById('ufile').style.margin = '5px 0px -5px 0px';
    document.getElementById('upload_response').style.display = 'none';
    document.getElementById('error').style.display = 'none';
    document.getElementById('error2').style.display = 'none';
    document.getElementById('abort').style.display = 'none';
    document.getElementById('warnsize').style.display = 'none';
    document.getElementById('progress_percent').innerHTML = '';
    var oProgress = document.getElementById('progress');
    oProgress.style.display = 'block';
    oProgress.style.width = '0px';

    // get form data for POSTing
    //var vFD = document.getElementById('upload_form').getFormData(); // for FF3
    var vFD = new FormData(document.getElementById('upload_form')); 

    // create XMLHttpRequest object, adding few event listeners, and POSTing our data
    var oXHR = new XMLHttpRequest();        
    oXHR.upload.addEventListener('progress', uploadProgress, false);
    oXHR.addEventListener('load', uploadFinish, false);
    oXHR.addEventListener('error', uploadError, false);
    oXHR.addEventListener('abort', uploadAbort, false);
    oXHR.open('POST', 'upload.php');
    oXHR.send(vFD);

    // set inner timer
    oTimer = setInterval(doInnerUpdates, 300);
}

function doInnerUpdates() { // we will use this function to display upload speed
    var iCB = iBytesUploaded;
    var iDiff = iCB - iPreviousBytesLoaded;

    // if nothing new loaded - exit
    if (iDiff == 0)
        return;

    iPreviousBytesLoaded = iCB;
    iDiff = iDiff * 2;
    var iBytesRem = iBytesTotal - iPreviousBytesLoaded;
    var secondsRemaining = iBytesRem / iDiff;

    // update speed info
    var iSpeed = iDiff.toString() + 'B/s';
    if (iDiff > 1024 * 1024) {
        iSpeed = (Math.round(iDiff * 100/(1024*1024))/100).toString() + 'MB/s';
    } else if (iDiff > 1024) {
        iSpeed =  (Math.round(iDiff * 100/1024)/100).toString() + 'KB/s';
    }

    document.getElementById('speed').innerHTML = iSpeed;
    document.getElementById('remaining').innerHTML = '| ' + secondsToTime(secondsRemaining);        
}

function uploadProgress(e) { // upload process in progress
    if (e.lengthComputable) {
        iBytesUploaded = e.loaded;
        iBytesTotal = e.total;
        var iPercentComplete = Math.round(e.loaded * 100 / e.total);
        var iBytesTransfered = bytesToSize(iBytesUploaded);

        document.getElementById('progress_percent').innerHTML = iPercentComplete.toString() + '%';
        document.getElementById('progress').style.width = (iPercentComplete * 4).toString() + 'px';
        document.getElementById('b_transfered').innerHTML = iBytesTransfered;
        if (iPercentComplete == 100) {
            var oUploadResponse = document.getElementById('upload_response');
            oUploadResponse.innerHTML = '<h1>Please wait...processing</h1>';
        }
    } else {
        document.getElementById('progress').innerHTML = 'unable to compute';
    }
}

function uploadFinish(e) { // upload successfully finished
    var oUploadResponse = document.getElementById('upload_response');
    oUploadResponse.innerHTML = e.target.responseText;

    document.getElementById('progress_percent').innerHTML = '100%';
    document.getElementById('progress').style.width = '400px';
    document.getElementById('filesize').innerHTML = sResultFileSize;
    document.getElementById('remaining').innerHTML = '| 00:00:00';

    clearInterval(oTimer);
}

function uploadError(e) { // upload error
    $('#errormessage').slideUp('fast', function() {
        $('#errormessage').html(uploadingcanceld);
        $('#errormessage').slideDown('fast');
    });
    clearInterval(oTimer);
}  

function uploadAbort(e) { // upload abort
    clearInterval(oTimer);
}

Answer 1

XHR是一个动态数据调用，它不是文档转发调用，这意味着我们开始使用XHR的原因是我们不希望将客户端转发到另一个页面以获取新内容到页面中。因此，您可能希望等待XHR完成发送数据的过程，通过XHR获取该传输的结果，并根据您的需要进行这些结果。

因此，实质上，您正在创建虚拟文档客户端/服务器传输和握手，而无需转发客户端，其中XHR是为了实现而创建的角色。

XMLHttpRequest不会发送到另一个页面

1 个答案: