Chrome Development Tool: [VM] file from javascript

Chrome Development Tool: [VM] file from javascript

[VM] (scriptId) has no special meaning. It's a dummy name假名 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.

Chrome Console: VM

It is abbreviation of the phrase Virtual Machine. In the Chrome JavaScript engine (called V8) each script has its own script ID.

Sometimes V8 has no information about the file name of a script, for example in the case of an eval. So devtools uses the text "VM" concatenated with the script ID as a title for these scripts.

Some sites may fetch many pieces of JavaScript code via XHR and eval it. If a developer wants to see the actual script name for these scripts she can use sourceURL. DevTools parses and uses it for titles, mapping etc.

https://blog.csdn.net/u010598271/article/details/53740778

chrome下调试本地js，不能设置断点，在控制台显示VM+数字+要调试的文件名。

解决方案：

1》、在调试<source>的左下方有一个{}图标，提示“pretty print”，点击，chrome就会另外打开一个:formatted的文件，在里面就可以调试了。

原因估计是chrome将源文件误认为是压缩过的，所以不能断点调试，重新格式化下就行了。

2》、清空缓存或重启浏览器