Toggle image on click
HTML
<script>
function change() {
var img1 = "http://placehold.it/350x150",
img2 = "http://placehold.it/200x200";
var imgElement = document.getElementById('test');
imgElement.src = (imgElement.src === img1)? img2 : img1;
}
</script>
<img src="http://placehold.it/350x150" id="test" onclick ="change();"/>