A huge codebase leads to "Maximum call stack size exceeded" error

[dkrupenya]

Steps to reproduce

1. Take ketcher-check.zip from this issue: vite build error epam/ketcher#5565 (comment)
2. Run npm i and npm run build. You get:

error during build:
[commonjs--resolver] Maximum call stack size exceeded
file: /ketcher-check/node_modules/ketcher-core/dist/index.modern.js
    at String.replace (<anonymous>)
    at isCommonjs (file:///ketcher-check/node_modules/vite-plugin-commonjs/dist/index.mjs:252:15)
    at transformCommonjs (file:///ketcher-check/node_modules/vite-plugin-commonjs/dist/index.mjs:413:8)
    at Object.transform (file:///ketcher-check/node_modules/vite-plugin-commonjs/dist/index.mjs:393:14)
    at file:///ketcher-check/node_modules/rollup/dist/es/shared/node-entry.js:22451:40

Reason

The issues is with this code when it is applied to a huge file (around 20Mb):

const multilineCommentsRE = /\/\*(.|[\r\n])*?\*\//gm;
const singlelineCommentsRE = /\/\/.*(?=[\n\r])/g;

function isCommonjs(code) {
  code = code.replace(multilineCommentsRE, "").replace(singlelineCommentsRE, "");
  return /\b(?:require|module|exports)\b/.test(code);
}

ChatGPT analysis:

The reason is catastrophic backtracking caused by the regex:

/\/\*(.|[\r\n])*?\*\//gm

Why this regex blows the stack

The sub-pattern: (.|[\r\n])*? is a catastrophic-backtracking trap:

(.) matches any character except newlines, [\r\n] matches only newlines

Together they form a redundant alternation that can match every character, but in an extremely inefficient way.

When the engine tries to match a long block of code, it repeatedly backtracks through countless combinations of (.) vs [\r\n].
This can grow exponentially and eventually ends in:

RangeError: Maximum call stack size exceeded

How to fix it

Use the standard “match any character” class in JavaScript:

const multilineCommentsRE = /\/\*[\s\S]*?\*\//g;

Or even better:

const multilineCommentsRE = /\/\*[^]*?\*\//g; // [^] = match any char, including newlines

This avoids backtracking traps and will not overflow the stack.