It is totally possible, i did something similar based on the example of Mike Sav. That's the html page and ther shoul be an external test.js file in the same folder
example.html:
<html>
<button type="button" value="Submit" onclick="myclick()" >
Click here~!
<div id='mylink'></div>
</button>
<script type="text/javascript">
function myclick(){
var myLink = document.getElementById('mylink');
myLink.onclick = function(){
var script = document.createElement("script");
script.type = "text/javascript";
script.src = "./test.js";
document.getElementsByTagName("head")[0].appendChild(script);
return false;
}
document.getElementById('mylink').click();
}
</script>
</html>
test.js:
alert('hello world')