Replace existing Image with New Image

Replace existing Image with New Image

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/1.2.1/lodash.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.4.8/fabric.min.js"></script>
<script src="http://promincproductions.com/gaTrackingJSFiddle.js"></script>
<canvas id="c" width="400" height="200"></canvas>
<span><input type="file" name="" id="span"></span>

CSS

canvas {
  border:1px solid lightgrey;
}

JavaScript

// file upload
var span = document.querySelector('#span');
span.onchange = function(e) {
    var file = e.target.files[0];
    var reader = new FileReader();
    reader.onload = function(file) {
        addImage(file.target.result);
    }
    reader.readAsDataURL(file);
}