<!DOCTYPE html>
<html>
<head>
</head>
<body>
<iframe id="iframe-id" src="your-source-file.htm"></iframe>
<script>
function set_iframe_src()
{
document.getElementById("iframe-id").src = "http://www.collectivesolver.com";
}
/*
run:
on button click iframe src with change to "http://www.collectivesolver.com"
*/
</script>
<button onclick="set_iframe_src()">Set iframe src</button>
<p id="p-id"></p>
</body>
</html>