javascript - Multiple files upload and using file reader to preview

Question

<input type='file' name="image"  onchange="preview(this);" multiple="multiple" />


window.preview = function (input){
        if(input.files && input.files[0]) {

            var reader = new FileReader();

            reader.readAsDataURL(input.files[0]);
            reader.onload = function(e){

                $("#previewImg").append("<img src='" + e.target.result +"'>");


            }
        }
    }

I have a function using file reader to preview image, It works fine in single file.

However I try to achieve multiple files.

My question is how to get input files array, loop files through file reader and append img

Answer 1

Javascript Solution Fiddle DEMO

 <input id="files" type="file" multiple="multiple" />
 <output id="result" />

Pure JavaScript:

function handleFileSelect(event) {
    //Check File API support
    if (window.File && window.FileList && window.FileReader) {

        var files = event.target.files; //FileList object
        var output = document.getElementById("result");

        for (var i = 0; i < files.length; i++) {
            var file = files[i];
            //Only pics
            if (!file.type.match('image')) continue;

            var picReader = new FileReader();
            picReader.addEventListener("load", function (event) {
                var picFile = event.target;
                var div = document.createElement("div");
                div.innerHTML = "<img class='thumbnail' src='" + picFile.result + "'" + "title='" + file.name + "'/>";
                output.insertBefore(div, null);
            });
            //Read the image
            picReader.readAsDataURL(file);
        }
    } else {
        console.log("Your browser does not support File API");
    }
}

document.getElementById('files').addEventListener('change', handleFileSelect, false);

---

jQuery Solution

jQuery File Input Image Preview Before It Is Uploaded

<form id="form1" runat="server">
    <input type='file' id="inputFile" />
    <img id="image_upload_preview" src="http://placehold.it/100x100" alt="your image" />
</form>

jQuery:

function readURL(input) {
    if (input.files && input.files[0]) {
        var reader = new FileReader();
        reader.onload = function (e) {
            $('#image_upload_preview').attr('src', e.target.result);
        }
        reader.readAsDataURL(input.files[0]);
    }
}

$("#inputFile").change(function () {
    readURL(this);
});