http://stackoverflow.com/questions/17367560/chrome-development-tool-vm-file-from-javascript
it says:
[VM] (scriptId) has no special meaning. It’s a dummy name to help us to distinguish code which are not directly tied to a file name, such as code created using eval and friends.
In the past, all of these scripts were just labelled (program).
If you’re interested, just look up "[VM]"in the source code of Chromium, you will discover that these numbers have no significant meaning outside the developer tools.
https://code.google.com/p/chromium/codesearch#search/&q="[VM]"&sq=package%3Achromium&type=cs
More tricks about javascript debugging could be found here:
https://developer.chrome.com/devtools/docs/javascript-debugging#breakpoints-dynamic-javascript
Test:
<html>
<script>
window.eval("console.log(\"ok\");debugger;");
//# sourceURL=dynamicScript.js
</script>
</html>
