Match end of Javascript code statement

Question

I would like to process/parse and alter some Javascript code, preferably in a regular expression if that's possible (open to suggestions). The purpose would be to insert a new code snippet after each statement in the JS.

For example:

The original Javascript:

while(true){

    Utils.log("hello world");
    Utils.sleep(1000);

}

Code snippet that I would like to insert:

checkPause();

So the new code would look like this:

while(true){

    checkPause();
    Utils.log("hello world");
    checkPause();
    Utils.sleep(1000);
    checkPause();

}
checkPause();

The example above is quite simple, but the real JS code could be more complex and could even be minified. The code could also miss out some semicolons ;

The term for this is "instrumentation", and this question has been asked before stackoverflow.com/questions/843546/… — tjltjl
– tjltjl, Commented Dec 6, 2012 at 15:49
@RocketHazmat: I'm building a program in C#, it makes use of the V8 engine & javascriptdotnet.codeplex.com to run some scripts. I need the script to check if it should pause. — Drahcir
– Drahcir, Commented Dec 6, 2012 at 15:50
This is not possible to do with a regex. Use a javascript parser for that. — Christoph
– Christoph, Commented Dec 6, 2012 at 15:53

teh_senaus · Accepted Answer · 2012-12-06 16:18:30Z

1

A very dirty way to do this would be to insert your snippet after every opening brace, closing brace, and semicolon. Like this:

 code.replace(/\;/g, '; checkPause(); ').replace(/\{/g, '{ checkPause(); ').replace(/\}/g, '} checkPause(); ')

A proper way would be to use a parser.

answered Dec 6, 2012 at 16:18

teh_senaus

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2 Comments

Drahcir Over a year ago

Thanks for your answer, I need to test more for my purpose but it seems to work. I have narrowed it down to Regex.Replace(code, @"\;|\{|\}|\n", @"$0 checkPause();") in C#.

tjltjl Over a year ago

Just be careful that your code doesn't include e.g. a = ";" :)

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