Chrome Development Tool: [VM] file from javascript

I added a breakpoint in my javascript file (jaydata.js) and was pressing "Step over to the next function call." When it got to a line that was:

},

another file titled "[VM] (8312)" popped up. I kept clicking "Step over to the next function call" and now my screen is:

What are these strange and mysterious scripts titled "[VM](XXXX " and where do they come from?

[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.

update 2015-06-25

[VM] (scriptId) was renamed to VMscriptId a while ago, and here is the direct link to search result in case the value changes again.

Whenever you load HTML content through AJAX, and that content contains <script> tags, the script will be evaluated using eval() and recognized by Chrome's Sources view as a new file beginning with 'VM'. You can always go to the Network tab, find the AJAX request, and view the HTML response in its entirety, including your script.