注释掉正则表达式，javascript

Question

Apologies if this has already been covered - perhaps i am searching for the wrong thing.

The following commented out line generates a syntax error:

/* /[foo].*/ */

It seems that the '*/' within the regex is confused with the end of the comment.

Is there a way to safely comment out blocks of code containing regular expressions?

Answer 1

This subject rises in many programming languages.

I mark places that look like comment ends with special chars, so I can easily find them later to undo the comment. First it looks like this:

 /* comment start here var emailBlabla = someString.replace(/^\s*/, '').replace(/\s*$/, ''); comment ends here */

Then:

 /* comment start here var emailBlabla = someString.replace(/^\sx*x/x, '').replace(/\s*$/, ''); // <<< note x*x/x comment ends here */

Now whenever I want to uncomment, I just look for the sequence x*x/x.

Note that this doesn't work with tags, eg context Fluid/TYPO3:

 <f:comment>

If you want to "deactivate" this tag without removing it, this won't work:

 x<fx:xcomment>

Because the parser still sees a tag with namespace, and the namespace just changed to fx. In the context of tags, you have to break with space.

 x < fx: xcomment>

But even then you have a clearly marked situation where you can work with find/replace.

Answer 2

It's an error because you can't include */ in the comment, otherwise it terminates the comment and then the last */ is left by itself to error out. Just add a space:

 /* /[foo].* / */

Or comment out the WHOLE line:

 // /[foo].*/

If you are possessing a string with code in it and adding comment blocks programmatically, then simply replace all */ with * / :

 var final = '/*' + code.replace(/\*\//g, '* /') + '*/';