HTML5 Drag and Drop Multiple File Uploader

Our new article is going to tell you about HTML5 file upload. Yes, I explained the basics of html5 file upload in the past (in one of our previous articles), but today I would like to give you another example, a better one. Now, you can just drag and drop your images (multiple images) in order to start uploading. Plus, the script displays the overall progress (in percentage, plus files left) and server response (without actual uploading). I am going to display the progress in a Canvas element in realtime. And, at  last – our script can upload files not only into its own server, but to another too (we can say that this is cross-site uploader).

Here are our demo and downloadable packages:

Ok, download the sources and let's begin !

Step 1. HTML

First – html markup:

<div class="container">
    <div class="contr"><h2>Drag and Drop your images to 'Drop Area' (up to 5 files at a time, size - under 256kb)</h2></div>
    <div class="upload_form_cont">
        <div id="dropArea">Drop Area</div>

        <div class="info">
            <div>Files left: <span id="count">0</span></div>
            <div>Destination url: <input id="url" value="http://www.script-tutorials.com/demos/257/upload.php"/></div>
            <h2>Result:</h2>
            <div id="result"></div>
            <canvas width="500" height="20"></canvas>
        </div>
    </div>
</div>
<script src="js/script.js"></script>

As you can see, it consists of several main elements: ‘Drop area’ at the left and ‘Info block’ at the right. When we drag and drop image files on our dropArea, in the Info block we will get a response from server. Pay attention to the ‘Destination url’ element. Right now it is connected to our server. But you can change it to your url anytime.

Step 2. CSS

Now, it's time to customize our layout:

.container {
    overflow:hidden;
    width:960px;
    margin:20px auto;
}
.contr {
    background-color: #212121;
    color: #FFFFFF;
    padding: 10px 0;
    text-align: center;

    border-radius:10px 10px 0 0;
    -moz-border-radius:10px 10px 0 0;
    -webkit-border-radius:10px 10px 0 0;
}
.upload_form_cont {
    background: -moz-linear-gradient(#ffffff, #f2f2f2);
    background: -ms-linear-gradient(#ffffff, #f2f2f2);
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #ffffff), color-stop(100%, #f2f2f2));
    background: -webkit-linear-gradient(#ffffff, #f2f2f2);
    background: -o-linear-gradient(#ffffff, #f2f2f2);
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#f2f2f2');
    -ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#f2f2f2')";
    background: linear-gradient(#ffffff, #f2f2f2);

    color: #000;
    overflow: hidden;
}
.info {
    background-color: #EEEEEE;
    border: 1px solid #DDDDDD;
    float: left;
    font-weight: bold;
    height: 530px;
    margin: 20px;
    position: relative;
    width: 560px;
}
.info > div {
    font-size: 14px;
    font-weight: bold;
    padding: 10px 15px 5px;
}
.info > h2 {
    padding: 0 15px;
}
.info > canvas {
    margin-left: 15px;
    margin-bottom: 10px;
}
.info #url {
    width: 400px;
}
#dropArea {
    background-color: #DDDDDD;
    border: 3px dashed #000000;
    float: left;
    font-size: 48px;
    font-weight: bold;
    height: 530px;
    line-height: 530px;
    margin: 20px;
    position: relative;
    text-align: center;
    width: 300px;
}
#dropArea.hover {
    background-color: #CCCCCC;
}
#dropArea.uploading {
    background: #EEEEEE url(loading.gif) center 30% no-repeat;
}
#result .s, #result .f {
    font-size: 12px;
    margin-bottom: 10px;
    padding: 10px;

    border-radius:10px;
    -moz-border-radius:10px;
    -webkit-border-radius:10px;
}
#result .s {
    background-color: #77fc9f;
}
#result .f {
    background-color: #fcc577;
}

Step 3. HTML5 JS

// variables
var dropArea = document.getElementById('dropArea');
var canvas = document.querySelector('canvas');
var context = canvas.getContext('2d');
var count = document.getElementById('count');
var destinationUrl = document.getElementById('url');
var result = document.getElementById('result');
var list = [];
var totalSize = 0;
var totalProgress = 0;

// main initialization
(function(){

    // init handlers
    function initHandlers() {
        dropArea.addEventListener('drop', handleDrop, false);
        dropArea.addEventListener('dragover', handleDragOver, false);
    }

    // draw progress
    function drawProgress(progress) {
        context.clearRect(0, 0, canvas.width, canvas.height); // clear context

        context.beginPath();
        context.strokeStyle = '#4B9500';
        context.fillStyle = '#4B9500';
        context.fillRect(0, 0, progress * 500, 20);
        context.closePath();

        // draw progress (as text)
        context.font = '16px Verdana';
        context.fillStyle = '#000';
        context.fillText('Progress: ' + Math.floor(progress*100) + '%', 50, 15);
    }

    // drag over
    function handleDragOver(event) {
        event.stopPropagation();
        event.preventDefault();

        dropArea.className = 'hover';
    }

    // drag drop
    function handleDrop(event) {
        event.stopPropagation();
        event.preventDefault();

        processFiles(event.dataTransfer.files);
    }

    // process bunch of files
    function processFiles(filelist) {
        if (!filelist || !filelist.length || list.length) return;

        totalSize = 0;
        totalProgress = 0;
        result.textContent = '';

        for (var i = 0; i < filelist.length && i < 5; i++) {
            list.push(filelist[i]);
            totalSize += filelist[i].size;
        }
        uploadNext();
    }

    // on complete - start next file
    function handleComplete(size) {
        totalProgress += size;
        drawProgress(totalProgress / totalSize);
        uploadNext();
    }

    // update progress
    function handleProgress(event) {
        var progress = totalProgress + event.loaded;
        drawProgress(progress / totalSize);
    }

    // upload file
    function uploadFile(file, status) {

        // prepare XMLHttpRequest
        var xhr = new XMLHttpRequest();
        xhr.open('POST', destinationUrl.value);
        xhr.onload = function() {
            result.innerHTML += this.responseText;
            handleComplete(file.size);
        };
        xhr.onerror = function() {
            result.textContent = this.responseText;
            handleComplete(file.size);
        };
        xhr.upload.onprogress = function(event) {
            handleProgress(event);
        }
        xhr.upload.onloadstart = function(event) {
        }

        // prepare FormData
        var formData = new FormData();
        formData.append('myfile', file);
        xhr.send(formData);
    }

    // upload next file
    function uploadNext() {
        if (list.length) {
            count.textContent = list.length - 1;
            dropArea.className = 'uploading';

            var nextFile = list.shift();
            if (nextFile.size >= 262144) { // 256kb
                result.innerHTML += '<div class="f">Too big file (max filesize exceeded)</div>';
                handleComplete(nextFile.size);
            } else {
                uploadFile(nextFile, status);
            }
        } else {
            dropArea.className = '';
        }
    }

    initHandlers();
})();

Most of code is already commented. I hope that you can understand all this code. Anyway – some explanation of how it works: in the beginning, we have linked two handlers to our DropArea: ‘drop’ and ‘dropover’. When we put our dragged files over our Drop area, we can apply custom styles to our drop area. Then, when we drop our files, our script starts executing ‘processFiles’ function (it pushs all the dropped files into array, and starts uploading them step by step). In the result, we send data through XMLHttpRequest object to custom recipient server. During sending the files, we also display overall progress at our canvas element.

Step 4. PHP

<?php

// set error reporting level
if (version_compare(phpversion(), '5.3.0', '>=') == 1)
  error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED);
else
  error_reporting(E_ALL & ~E_NOTICE);

function bytesToSize1024($bytes, $precision = 2) {
    $unit = array('B','KB','MB');
    return @round($bytes / pow(1024, ($i = floor(log($bytes, 1024)))), $precision).' '.$unit[$i];
}

if (isset($_FILES['myfile'])) {
    $sFileName = $_FILES['myfile']['name'];
    $sFileType = $_FILES['myfile']['type'];
    $sFileSize = bytesToSize1024($_FILES['myfile']['size'], 1);

    echo <<<EOF
<div class="s">
    <p>Your file: {$sFileName} has been successfully received.</p>
    <p>Type: {$sFileType}</p>
    <p>Size: {$sFileSize}</p>
</div>
EOF;
} else {
    echo '<div class="f">An error occurred</div>';
}