Thursday, June 13, 2013

Commenting out JavaScript regular expressions in Node.js

Weird oddity commenting out code

This line works fine:

hc = hc.replace(/path=[^;]*/,"path=/"+hostMap[pref]);

However, if I try to comment out a block using /* */, things get wonky:

hc = hc.replace(/path=[^;]*/,"path=/"+hostMap[pref]);

The JavaScript interpreter throws a nice syntax error.
It turns out that the JavaScript interpreter sees the /* and says "cool, its a comment. I'll go until I see it close." Then it sees the */ of the regular expression and says "ok, I'm done."
It is left with some seemingly bogus line:

Now, if you could make this appear to be legitimate, you could get some seriously obfuscated code going.

The workaround is to comment out the line with the // mechanism:

//hc = hc.replace(/path=[^;]*/,"path=/"+hostMap[pref]);

Now if I could just figure out how to get chrome to start showing spell-check suggestions again...

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