<!DOCTYPE html>
<html lang="en-US">
<body>
<img width="200" heigth="200">
<p>Click the button to add 'src' for the image</p>
<button onclick="myFunction()">Click Me</button>
<script>
var image = document.getElementsByTagName("img")[0];
function myFunction(){
var att = document.createAttribute("src");
att.value = "wikimass.png";
image.setAttributeNode(att);
}
</script> </body>
</html>