Decomment

Common errors

• Error: Line X: Unexpected token

  cause The input JavaScript or JSON code contains syntax errors or non-standard constructs that Esprima cannot parse strictly.
  fix Correct the syntax errors in your code. For less strict parsing, upgrade to `decomment` v0.9.4 or higher and use `decomment(code, { tolerant: true })`.

• TypeError: decomment is not a function

  cause Attempting to import `decomment` using a named import or an incorrect CommonJS `require` pattern, when it is the default/module.exports.
  fix For CommonJS, use `const decomment = require('decomment');`. For ESM, use `import decomment from 'decomment';`.

Warnings

• breaking Support for Node.js versions 0.10 and 0.12 was dropped starting with version 0.9.0. The last version to support these legacy environments was 0.8.8.
  Fix: Upgrade your Node.js environment to version 4, 6, 8, or newer (minimum Node.js 6.4 required).
• gotcha The library does not support mixed content. If the input is recognized as HTML, only HTML comments (`<!-- -->`) will be removed, ignoring any JavaScript or CSS comments embedded within script or style tags.
  Fix: For mixed content, consider using separate parsing steps for each language or a more specialized tool that understands embedded languages.
• gotcha By default, Decomment performs strict JavaScript parsing via Esprima. If the input JavaScript or JSON code is syntactically invalid, the parser will throw an error.
  Fix: Ensure your input code is valid JavaScript or JSON. Alternatively, use the `tolerant: true` option (available since 0.9.4) to potentially handle some non-strict constructs or errors more gracefully, though this might not guarantee full parsing.
• gotcha The `tolerant` option, which allows for less strict JavaScript parsing, was introduced in version 0.9.4. Prior versions perform strictly compliant parsing.
  Fix: If encountering parsing errors with non-strict JavaScript in older versions, upgrade to >=0.9.4 and use the `{ tolerant: true }` option.

Install

• npm install decomment npm
• yarn add decomment yarn
• pnpm add decomment pnpm

Imports

• decomment
  wrong:

  const decomment = require('decomment').decomment;

  correct:

  import decomment from 'decomment';

  The library primarily exports the main decomment function as the default export (CommonJS `module.exports` or ESM `default`).
• decomment

  const decomment = require('decomment');

  This is the documented CommonJS import method for Node.js environments.

Quickstart

Demonstrates basic usage of the `decomment` function to remove various types of comments from a JavaScript string, including preserving layout.

import decomment from 'decomment';

const jsCode = 'var t; // This is a single-line comment\n/*\n * This is a multi-line comment\n */\nconst obj = { /* inline */ key: 'value' };\n// Another line with a comment\nconsole.log(t);';

const cleanedCode = decomment(jsCode);
console.log('--- Original Code ---');
console.log(jsCode);
console.log('\n--- Cleaned Code (default) ---');
console.log(cleanedCode);
// Example with space option to preserve layout
const preservedLayoutCode = decomment(jsCode, { space: true });
console.log('\n--- Cleaned Code (space: true) ---');
console.log(preservedLayoutCode);