RegEx change function name and parameter of string

Question

I'm awful with RegEx to begin with. Anyway I tried my best and think I got pretty far, but I'm not exactly there yet...

What I have: A javascript source file that I need to process in Node.js. Can look like that:

var str = "require(test < 123)\n\nrequire(test2 !== test)\n\nfunction(dontReplaceThisParam) {\n    console.log(dontReplaceThisParam)\n}";

What I came up with:

console.log(str.replace(/\(\s*([^)].+?)\s*\)/g, 'Debug$&, \'error_1\''))

Theres a few problems:

I want that the string error gets inside the paranthesis so it acts as a second parameter.
All function calls, or I think even everything with paranthesis will be replaced. But only function calls to "require(xxx)" should be touched.
Also, the error codes should somehow increment if possible...

So a string like "require(test == 123)" should convert to "requireDebug(test == 123, 'error_N')" but only calls to "require"...

What currently gets outputted by my code:

requireDebug(test < 123), 'error_1'

requireDebug(test2 !== test), 'error_1'

functionDebug(dontReplaceThisParam), 'error_1' {
    console.logDebug(dontReplaceThisParam), 'error_1'
}

What I need:

requireDebug(test < 123, 'error_1')

requireDebug(test2 !== test, 'error_2')

function(dontReplaceThisParam) {
    console.log(dontReplaceThisParam)
}

I know I could just do things like that manually but we're talking here about a few hundred source files. I also know that doing such things is not a very good way, but the debugger inside the require function is not working so I need to make my own debug function with an error code to locate the error. Its pretty much all I can do at the moment...

Any help is greatly appreciated!

llama · Accepted Answer · 2017-09-27 13:52:18Z

1

Start the regex with require, and since you need an incrementing counter, pass a function as the second arg to replace, so that you can increment and insert the counter for each match.

var str = "require(test < 123)\n\nrequire(test2 !== test)\n\nfunction(dontReplaceThisParam) {\n    console.log(dontReplaceThisParam)\n}";
var counter = 0;

console.log(str.replace(/require\(\s*([^)].+?)\s*\)/g, (s, g2) => 
  `requireDebug(${g2}, \'error_${++counter}\')`
));

Other than that, your code was unaltered.

answered Sep 27, 2017 at 13:52

llama

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2 Comments

David Fariña Over a year ago

Holy cow! You make this look so easy * ashamed * Thank you very much!

llama Over a year ago

You're welcome, but it was easy since you wrote the majority of the regex. I just added a word. :)

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