skip-regex: Literal Regular Expression Detector

1.0.2 · abandoned · verified Tue Apr 21

skip-regex is a lightweight, zero-dependency JavaScript utility designed for the highly accurate and fast detection of literal regular expressions within a string. It is currently at version 1.0.2, with its last release in December 2018, indicating an abandoned or maintenance status rather than active development. The library provides a single function, `skipRegex(source: string, start: number)`, which identifies the end position of a regex given a starting slash. Its key differentiators include a minimal footprint, compatibility across NodeJS, various bundlers, and browsers (including IE9+), and comprehensive TypeScript definitions. This makes it suitable for parsing or code analysis tools that need to distinguish between division operators, comments, and regex literals reliably.

Common errors

```
Module '"skip-regex"' has no default export. Did you mean to use 'import skipRegex = require("skip-regex")'?
```
cause Using `import skipRegex from 'skip-regex'` in a TypeScript project without `esModuleInterop` enabled in `tsconfig.json`.

fix Enable `esModuleInterop: true` in your `tsconfig.json` or change the import statement to `import skipRegex = require('skip-regex')`.

Warnings

gotcha The `start` parameter provided to `skipRegex` *must* point to a forward slash (`/`) character within the `source` string. If `start` points to any other character, the function's behavior is undefined or incorrect.
Fix: Always ensure `source[start] === '/'` before calling `skipRegex(source, start)`. Use `source.indexOf('/')` to find valid starting points for a potential regex.

Install

npm install skip-regex npm
yarn add skip-regex yarn
pnpm add skip-regex pnpm

Imports

skipRegex
```
import skipRegex from 'skip-regex'
```
This is the standard ESM import. For TypeScript, `esModuleInterop` should be enabled in `tsconfig.json` for this style.

skipRegex

wrong:

import skipRegex from 'skip-regex' // without esModuleInterop in TypeScript

correct:

const skipRegex = require('skip-regex')

This is the CommonJS import pattern, suitable for Node.js or bundlers configured for CJS.

skipRegex
wrong:
```
import { skipRegex } from 'skip-regex' // Incorrect for default export
```
correct:
```
import skipRegex = require('skip-regex')
```
This TypeScript-specific import syntax explicitly uses a `require`-style import, useful when `esModuleInterop` is not enabled.

Quickstart

This quickstart demonstrates how to iterate through a string to find and extract all literal regular expressions using `skipRegex`, differentiating them from division operators or comment starts.

import skipRegex from 'skip-regex'

const source = 'const foo = bar /.*/g; // this is a regex \n const baz = 10 / 2; // division \n const qux = /* comment */ 5;'
let start = 0;
let currentIndex = 0;
let detectedRegexes = [];

while (currentIndex < source.length) {
  start = source.indexOf('/', currentIndex);
  if (start === -1) break;

  const end = skipRegex(source, start);

  if (end > start + 1) {
    // Detected as regex if end is greater than start + 1 (meaning it found a regex beyond the initial slash)
    const regex = source.slice(start, end);
    detectedRegexes.push({ regex, start, end });
    currentIndex = end;
  } else {
    // Not a regex, could be division or comment start.
    // skipRegex returns start + 1 if it's not a regex, so we advance past the current slash.
    currentIndex = start + 1;
  }
}

console.log('Detected Regular Expressions:', detectedRegexes);
// Example output shows how it distinguishes:
// Detected Regular Expressions: [
//   { regex: '/.*/g', start: 16, end: 22 }
// ]

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