pegjs-loader

library0.5.8jsnpmunverified

A webpack loader that compiles PEG.js grammar files into JavaScript parser modules. Current version 0.5.8 is stable with weekly npm downloads around 1,000. Requires peer dependencies PEG.js ^0.10.0 and webpack >=1. Supports options like cache, optimize, trace, allowedStartRules, and dependencies. Differentiated from alternatives like jison-loader by its tight integration with PEG.js and support for multiple parser options via query parameters.

serialization devops

npm install pegjs-loader

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · PEGJS-LOADER

pegjs-loader

serializationjavascriptv0.5.8

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

pegjs-loader

✓ module.exports = { module: { loaders: [{ test: /\.pegjs$/, loader: 'pegjs-loader' }] } }

✗ import pegjs from 'pegjs-loader'

This is a webpack loader, not a JavaScript module. It is configured in webpack.config.js, not imported in application code.

parser

✓ const parser = require('./parser.pegjs');

✗ const parser = require('pegjs-loader!./parser.pegjs');

If configured in webpack config, simply require the .pegjs file. Inline loader syntax is also possible but less common.

parser (with options)

✓ const parser = require('pegjs-loader?cache=true!./parser.pegjs');

✗ const parser = require('./parser.pegjs?cache=true');

Options are passed as query parameters to the loader, not to the grammar file.

Configure webpack to use pegjs-loader on .pegjs files, then require and parse with the compiled parser.

// webpack.config.js module.exports = { entry: './src/index.js', output: { filename: 'bundle.js' }, module: { loaders: [ { test: /\.pegjs$/, loader: 'pegjs-loader?cache=true&optimize=size' } ] } }; // src/index.js const parser = require('./grammar.pegjs'); const result = parser.parse('input string'); console.log(result);

Debug

Known issues

breakingPEG.js updated to 0.10.0, requiring changes in grammar syntax

fix

Update grammars to be compatible with PEG.js 0.10.0. Refer to PEG.js changelog.

affects: >=0.5.0

deprecatedwebpack 1 loaders syntax is deprecated; webpack 2+ uses 'rules' instead of 'loaders'

fix

Use module.rules: [{ test: /\.pegjs$/, use: 'pegjs-loader' }] in webpack 2+.

affects: >=0.5.1

gotchaOptions must be passed as query parameters; they cannot be set in a separate options object

fix

Append options as query string: 'pegjs-loader?cache=true'.

affects: >=0.3.0

breakingPEG.js 0.9.0 breaking changes (e.g., no more global PEG object)

fix

Ensure grammar files are compatible with PEG.js 0.9.0+

affects: >=0.2.1

Errors

Common errors & fixes

Error: Cannot find module 'pegjs'

pegjs not installed in node_modules

fix

npm install --save-dev pegjs

Module build failed: Error: Couldn't find preset 'es2015' relative to directory

Webpack config requires babel-loader for .js files, but pegjs-loader doesn't use babel

fix

Ensure pegjs-loader is not processed by babel; exclude node_modules or pegjs-loader from babel-loader rule

TypeError: Cannot read property 'cacheable' of undefined

Bug in pegjs-loader v0.2.0

fix

Upgrade pegjs-loader to v0.2.2 or later

Error: path must be a string

Passing non-string options as query parameters

fix

Ensure all loader options are strings (e.g., 'true' instead of true)

Upgrade

Version history

0.5.8latest on npm

Audit

Dependencies

pegjsrequiredPeer dependency: compiles grammar files

webpackrequiredPeer dependency: loader runs in webpack

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/eploko/pegjs-loader ↗

packagehttps://www.npmjs.com/package/pegjs-loader ↗

homepagehttp://eploko.github.io/pegjs-loader ↗