troubleshooting Question

How to Resize an Image on Upload with JavaScript

Avatar of Michael Vasilevsky
Michael VasilevskyFlag for United States of America asked on
JavaScript* canvas
2 Comments1 Solution176 ViewsLast Modified:
I'm trying to resize a photo on upload using JavaScript but can't get it. I'm using the below code (also here). I want to resize any photo to a maximum size of 800x600.

The commented out
is what I want to work:

<input id="getFile" type="file" accept="image/*"/>
<img class="pic" src="" />

var readURL = function(input) {
  if (input.files[0]) {
    var reader = new FileReader();

    reader.onload = function (e) {

$("#getFile").on('change', function(){

function resizeMe(file) {
    var dataURL = "x";
    var reader = new FileReader();
    reader.onloadend = function () {

        var tempImg = new Image();
        tempImg.src = reader.result;
        tempImg.onload = function () {

            var MAX_WIDTH = 800;
            var MAX_HEIGHT = 600;
            var tempW = tempImg.width;
            var tempH = tempImg.height;
            if (tempW > tempH) {
                if (tempW > MAX_WIDTH) {
                    tempH *= MAX_WIDTH / tempW;
                    tempW = MAX_WIDTH;
            } else {
                if (tempH > MAX_HEIGHT) {
                    tempW *= MAX_HEIGHT / tempH;
                    tempH = MAX_HEIGHT;

            var canvas = document.createElement('canvas');
            canvas.width = tempW;
            canvas.height = tempH;
            var ctx = canvas.getContext("2d");
            ctx.drawImage(this, 0, 0, tempW, tempH);
            dataURL = canvas.toDataURL("image/jpeg");


    return dataURL;
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