preview image file upload javascript
<input type="file" accept="image/*" onchange="loadFile(event)">
<img id="output"/>
<script>
var loadFile = function(event) {
var output = document.getElementById('output');
output.src = URL.createObjectURL(event.target.files[0]);
output.onload = function() {
URL.revokeObjectURL(output.src) // free memory
}
};
</script>