remove cstyle comments (rm-cstyle-cmts)

remove c style comments from text file. (javascript source, json file etc)

This module removes comments from source files such as typescript and javascript.
It does not remove lines that are meaningful to typescript, such as @ts-ignore and <reference types="node"/>,
but removes other single line comments and multi line comments.
For other single line comment and multi line comment, it is possible to control which comment is removed by setting scan listener.
This module is much faster than the popular comment removal module.
gulp plugin is available.
web version is available.
new property keepJsDoc (v3.3.11)
regex flags strict check (v3.3.15)
- Even if it is not written as a regular expression in the text,
  it will be detected if it is valid as a regex (this is by design).

install

npm

$ npm install rm-cstyle-cmts --save-dev  
# shorthand  
$ npm i rm-cstyle-cmts -D

yarn
```
$ yarn add rm-cstyle-cmts -D
```

Features

remove mode

const rmc = require("rm-cstyle-cmts");
const removed = rmc("<source file content>");

walkthrough mode (walkthrough mode does things like statistics for source code comments by setting a scan listener.)

const rmc = require("rm-cstyle-cmts");

/** @type {Map<string, number>} */
const tagStatistics = new Map();
/**
 * Take statistics for jsDoc tag
 *
 * @param {object} context
 * @param {TScannerEventContext["event"]} context.event - currently EScannerEvent.(SingleLineComment | MultiLineComment) only
 * @param {TScannerEventContext["fragment"]} context.fragment comment body
 * @param {TScannerEventContext["offset"]} context.offset - fragment start offset from original source
 */
function handleScanEvent({ event, fragment, offset }) => {
  if (event === /*EScannerEvent.MultiLineComment*/1) {
      if (/^\/\*\*[^*]/.test(fragment)) {
          const re = /(?<=[\s\*{])@\w+(?=\s)/g;
          /** @type {RegExpExecArray} */
          let m;
          while (m = re.exec(fragment)) {
              const tag = m[0];
              let count = tagStatistics.get(tag) || 0;
              tagStatistics.set(tag, count + 1);
          }
      }
  }
  return true;
}

// At current implementation, accept one listener only
rmc.setListener(handleScanEvent);
rmc.walk("<source file content>");

API

node module.

const rmc = require("rm-cstyle-cmts");

run as remove mode

const opt = { collectRegex: true, showErrorMessage: true, preserveBlanks: true };
const removed = rmc("<source file content>", opt);

source {string} -- The target source content.
opt {object}
- opt.collectRegex {true | undefined} -- Whether collect detected regex. Default: undefined.
- opt.showErrorMessage {true | undefined} -- Whether to display an error message. Default: undefined.
- opt.preserveBlanks {true | undefined} -- Whether preserve whitespace and blank lines. Default: undefined.
- opt.path {string | undefined} -- Optional file path for regex detection details. Default: undefined.

run as walkthrough mode

const opt = { collectRegex: true, showErrorMessage: true };
rmc.walk("<source file content>", opt);

source {string} -- The target source content.
opt {object}
- opt.collectRegex {true | undefined} -- Whether collect detected regex. Default: undefined.
- opt.showErrorMessage {true | undefined} -- Whether to display an error message. Default: undefined.
- opt.path {string | undefined} -- Optional file path for regex detection details. Default: undefined.

Regex detection details (since v3.4.0)

When collectRegex: true is enabled, you can inspect detected regex literals via rmc.getDetectedReContext(). If you also provide opt.path, each detection includes file path and position information.

const fs = require("fs");
const rmc = require("rm-cstyle-cmts");

const path = "src/demo.js";
const opt = { collectRegex: true, path };
const result = rmc(fs.readFileSync(path, "utf8"), opt);

const { detectedReLiterals, uniqReLiterals } = rmc.getDetectedReContext();

// detectedReLiterals entries are:
// - string (legacy format, when opt.path is not provided)
// - [path, "line:x,column:y", "/.../flags"] (when opt.path is provided)
detectedReLiterals.forEach((item) => {
  if (typeof item === "string") {
    console.log("regex:", item);
    return;
  }
  const [filePath, position, regex] = item;
  console.log("regex:", regex, "at", position, "in", filePath);
});

// uniqReLiterals is the unique list of regex literal strings.
console.log("uniq:", uniqReLiterals);

// NOTE: Reset this context between independent file validations.
rmc.reset();

Playground

rm-cstyle-cmts Playground (powered by monaco-editor)

Performance measurement with `Benchmark.js`

$ npm run benchmark

We are comparing the process of deleting only comment from the following sample

Details

const json = `// see: http://json.schemastore.org/tsconfig
{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    // "allowJs": true,                       /* Allow javascript files to be compiled. */
    // "checkJs": true,                       /* Report errors in .js files. */
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    // "outDir": "./",                        /* Redirect output structure to the directory. */

    /* Strict Type-Checking Options */
    "strict": true,                           /* Enable all strict type-checking options. */
    // "strictNullChecks": true,              /* Enable strict null checks. */
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */

    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. */

    /* Module Resolution Options */
    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */

    /* Experimental Options */
    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
  },
  "files": [
    "y"
  ]
}`;

node v22.20.0

yarn run v1.22.22
$ node bench.mjs
Platform info:
Windows_NT 10.0.19045 x64
Node.JS: 22.20.0
V8     : 12.4.254.21-node.33
Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz x 8

strip-comments x 11,020 ops/sec ±1.26% (88 runs sampled)
strip-json-comments x 15,837 ops/sec ±0.60% (95 runs sampled)
rm-cstyle-cmts x 210,011 ops/sec ±0.09% (97 runs sampled)
rm-cstyle-cmts (webpack) x 183,336 ops/sec ±3.17% (88 runs sampled)
rm-cstyle-cmts (umd) x 198,935 ops/sec ±0.40% (90 runs sampled)
- - done - -
all results are equals? true # see NOTE
Done in 27.84s.

node v25.2.1

yarn run v1.22.22
$ node bench.mjs
Platform info:
Windows_NT 10.0.19045 x64
Node.JS: 25.2.1
V8     : 14.1.146.11-node.14
Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz x 8

strip-comments x 11,544 ops/sec ±0.25% (92 runs sampled)
strip-json-comments x 16,512 ops/sec ±0.18% (95 runs sampled)
rm-cstyle-cmts x 208,505 ops/sec ±0.58% (92 runs sampled)
rm-cstyle-cmts (webpack) x 215,666 ops/sec ±0.37% (90 runs sampled)
rm-cstyle-cmts (umd) x 214,950 ops/sec ±0.89% (90 runs sampled)
- - done - -
all results are equals? true # see NOTE
Done in 27.53s.

NOTE: strip-comments may be buggy and is excluded from comparison

The `Walkthrough mode`

Walkthrough mode does not modify original source.

The current implementation calls the listener on line comment and multi-line comment scan events.

import * as rmc from "rm-cstyle-cmts";

/**
 * @param {object} context
 * @param {TScannerEventContext["event"]} context.event - currently EScannerEvent.(SingleLineComment | MultiLineComment) only
 * @param {TScannerEventContext["fragment"]} context.fragment comment body
 * @param {TScannerEventContext["offset"]} context.offset - fragment start offset from original source
 */
function handleScanEvent({ event, fragment, offset }) => {
  if (event === /*EScannerEvent.MultiLineComment*/1) {
    // remove mode: preserve JSDoc comment
    // walkthrough mode: whether proceed walkthrough
    return /^\/\*\*[^*]/.test(fragment);
  }
  return false;
}
// At current implementation, accept one listener only
rmc.setListener(handleScanEvent);

const opt = { collectRegex: true, showErrorMessage: true };
rmc("<commented source>", opt);
rmc.walk("<commented source>", opt);

NOTE: Handling of listener in remove mode and walkthrough mode

In walkthrough mode: Returns true to continue processing. otherwise stop processing.
In remove mode: it returns true to preserve in the line comment and multi line comment deletion process.

`rm-cstyle-cmts` gulp plugin

gulp plugin sample task

sample task to scan javascript related files directly under node_modules

$ npm run grmc-test:cjs

API of gulp plugin

const gulp = require("gulp"); 
const grmc = require("rm-cstyle-cmts/cjs/gulp/");
const grmcOpt = {
    preserveBlanks: undefined, // remove blank lines and trailing whitespace
    renderProgress: true,      // show progress
    // isWalk: true // want walk through?
};
gulp.src(["./src/**/*.{js,jsx,ts,tsx}"]).pipe(
    grmc.getTransformer(grmcOpt)
).pipe(gulp.dest("./tmp"));

gulp plugin options

preserveBlanks {true | undefined} -- Whether preserve whitespace and blank lines. Default: undefined.
renderProgress {true | undefined} -- log scan source path(relative) currently being processed. Default: undefined.
collectRegex {true | undefined} -- Whether collect detected regex. Default: undefined.
isWalk {true | undefined} -- Whether to run in walkthrough mode. Default: undefined.
extraExtensions {string[] | undefined} -- Add additional extensions. Default: undefined.
disableDefaultExtensions {true | undefined} -- use extraExtensions only, instead of defaultExtensions. Default: undefined.
- defaultExtensions - ".js", ".jsx", ".ts", ".tsx", ".cjs", ".mjs", ".cts", ".mts"
timeMeasure {true | undefined} -- Whether to record the processing time for each file (replace mode only). Default: undefined.

example with `scan listener`

const gulp = require("gulp"); 
const grmc = require("rm-cstyle-cmts/cjs/gulp/");

// set scan event listener
grmc.getRmcInterface().setListener(({ event, fragment, offset }) => {
    if (event === /*EScannerEvent.MultiLineComment*/1) {
        // true: Concatenate fragment to result in "remove mode", continue walkthrough in "walkthrough mode".
        // false: remove fragment in "remove mode", stop walkthrough in "walkthrough mode".
        return /^\/\*(\*|!)\s/.test(fragment);
    }
    else if (event === /*EScannerEvent.SingleLineComment*/0) {
        return /(?:\/\/\/?\s+@ts-\w+|\/\/\/\s*<reference)/.test(fragment);
    }
    // remove fragment in "remove mode", stop walkthrough in "walkthrough mode".
    return false;
});

gulp.src(["./src/**/*.{js,jsx,ts,tsx}"]).pipe(
    /**
     * preserveBlanks : keep blank line and whitespaces, default is `undefined`.
     */
    grmc.getTransformer({
        preserveBlanks: undefined, // remove blank lines and trailing whitespace
        renderProgress: true,      // show progress
        // isWalk: true // want walk through?
    })
).pipe(gulp.dest("./tmp"));

rm-cstyle-cmts web version

You can use web version from cdn such as jsdelivr.
- can use the API through the Rmc global variable.

<!-- or https://cdn.jsdelivr.net/npm/rm-cstyle-cmts@latest/umd/index.min.js -->
<script src="https://cdn.jsdelivr.net/npm/rm-cstyle-cmts@3/umd/index.min.js"></script>

const source = `
///  <reference types="node"/>

import React from "react";
import ReactDOM from "react-dom";

/**
 * jsdoc comment
 */
function App() {
  return (
    // TODO: can optionally include quote string in react syntax.
    // such source input does not complete successfully.
    <h1>Hello's world's</h1>
  );
}

ReactDOM.render(<App />, document.getElementById("root"));
`;

/**
 * You can use the API through the `Rmc` global variable.
 */
console.log(Rmc(source));
// print detected regex literals detail (in this case, nothing any result)
console.log(Rmc.getDetectedReContext());
// reset of related statistics
Rmc.reset();

usage

Case: single line input (js)

const rmc = require("rm-cstyle-cmts");
const input = "    /** block comment */ const a = \"this is apple! \\n\", b = 'quoted \"strings\"', \
c = `list:\\n1. \${a}\\n2. \${b}\\n\${ /* comments */ ` - len: \${a.length + b.length}`}\\n ---`;  \
/* . */  let i = 2, n = 12 / 4 * 7/i; // last coment.  !";

const result = rmc(input);
console.log(result);
//> const a = "this is apple! \n", b = 'quoted "strings"', c = `list:\n1. ${a}\n2. ${b}\n${ /* comments */ ` - len: ${a.length + b.length}`}\n ---`;    let i = 2, n = 12 / 4 * 7/i;

Case: json source

const rmc = require("rm-cstyle-cmts");
const json = `// see: http://json.schemastore.org/tsconfig
{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    // "allowJs": true,                       /* Allow javascript files to be compiled. */
    // "checkJs": true,                       /* Report errors in .js files. */
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    // "outDir": "./",                        /* Redirect output structure to the directory. */

    /* Strict Type-Checking Options */
    "strict": true,                           /* Enable all strict type-checking options. */
    // "strictNullChecks": true,              /* Enable strict null checks. */
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */

    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. */

    /* Module Resolution Options */
    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */

    /* Experimental Options */
    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
  },
  "files": [
    "y"
  ]
}`;

const result = rmc(input);
console.log(result);
//> {
//>   "compilerOptions": {
//>     "target": "es5",
//>     "module": "commonjs",
//>     "strict": true,
//>     "esModuleInterop": true
//>   },
//>   "files": [
//>     "y"
//>   ]
//> }

Name		Name	Last commit message	Last commit date
Latest commit History 844 Commits
.circleci		.circleci
.github/workflows		.github/workflows
.vscode		.vscode
__tests__		__tests__
etc		etc
logs		logs
samples		samples
scripts		scripts
src		src
.gitignore		.gitignore
.gitpod.yml		.gitpod.yml
.yarnclean		.yarnclean
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
eslint.config.mjs		eslint.config.mjs
jest.config.js		jest.config.js
package.json		package.json
renovate.json		renovate.json
tsconfig.json		tsconfig.json
webpack.config.mjs		webpack.config.mjs
yarn.lock		yarn.lock

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remove cstyle comments (rm-cstyle-cmts)

install

Features

API

run as remove mode

run as walkthrough mode

Regex detection details (since v3.4.0)

Playground

Performance measurement with `Benchmark.js`

node v22.20.0

node v25.2.1

The `Walkthrough mode`

`rm-cstyle-cmts` gulp plugin

gulp plugin sample task

API of gulp plugin

gulp plugin options

example with `scan listener`

rm-cstyle-cmts web version

usage

Case: single line input (js)

Case: json source

About

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jeffy-g/rm-cstyle-cmts

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Repository files navigation

remove cstyle comments (rm-cstyle-cmts)

install

Features

API

run as remove mode

run as walkthrough mode

Regex detection details (since v3.4.0)

Playground

Performance measurement with Benchmark.js

node v22.20.0

node v25.2.1

The Walkthrough mode

rm-cstyle-cmts gulp plugin

gulp plugin sample task

API of gulp plugin

gulp plugin options

example with scan listener

rm-cstyle-cmts web version

usage

Case: single line input (js)

Case: json source

About

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License

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Watchers

Forks

Releases 44

Packages 0

Uh oh!

Contributors 6

Uh oh!

Languages

Performance measurement with `Benchmark.js`

The `Walkthrough mode`

`rm-cstyle-cmts` gulp plugin

example with `scan listener`

Packages