HTML file input image preview

<input type="file">
<img id="preview">

<script>
document.querySelector('[type=file]').onchange = function() {
    if(this.files && this.files[0]) {
        var reader = new FileReader();

        reader.onload = function (e) {
            document.getElementById('preview').src = e.target.result;
        }
        reader.readAsDataURL(this.files[0]);
    }
}
</script>