Registry / http-networking / preprocess-loader

preprocess-loader

library0.3.0jsnpmunverified

A webpack loader that uses the preprocess library to conditionally include or exclude code in HTML, JavaScript, CoffeeScript, and other module files based on custom or environment configurations. Version 0.3.0 is the latest stable release (the project appears inactive since 2017). It supports Webpack 1 and 2+ and allows overriding preprocess options via the `ppOptions` query parameter. Similar to gulp-preprocess, it provides directive syntax for conditional compilation (@if, @ifdef, @echo, @include). The loader is typically placed before other loaders in a chain to preprocess files before they are transpiled.

http-networking devops

npm install preprocess-loader

github ↗package ↗

INSTALL

IMPORT

SIG · PREPROCESS-LOADER

preprocess-loader

http-networkingjavascriptv0.3.0

Install

—

Import

—

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.

default

✓ import PreprocessLoader from 'preprocess-loader'

✗ const PreprocessLoader = require('preprocess-loader')

As a webpack loader, it is not typically imported directly; it is configured in webpack.config via loader name string 'preprocess-loader'. The import pattern is uncommon but shown for completeness.

useLoader

✓ module.exports = { module: { rules: [ { test: /\.js$/, use: 'preprocess-loader?+DEBUG' } ] } }

✗ module.exports = { module: { loaders: [ { test: /\.js$/, loader: 'preprocess-loader?+DEBUG' } ] } }

Webpack 2+ uses `rules` and `use` instead of `loaders`. The old `loaders` array is deprecated.

queryOptions

✓ use: [ { loader: 'preprocess-loader', options: { DEBUG: true, NODE_ENV: 'production' } } ]

✗ use: [ { loader: 'preprocess-loader?DEBUG=true&NODE_ENV=production' } ]

Webpack 2+ supports the `options` object. Query string may still work but is less maintainable.

Webpack 2+ configuration using preprocess-loader with environment variables and Babel.

// webpack.config.js module.exports = { module: { rules: [ { test: /\.js$/, use: [ { loader: 'preprocess-loader', options: { DEBUG: process.env.DEBUG === 'true' ? true : false, NODE_ENV: process.env.NODE_ENV ?? 'production' } }, 'babel-loader' ] } ] } }; // In your source.js const configValue = '/* @echo FOO */' || 'default value'; // @ifdef DEBUG console.log('Debugging enabled'); // @endif

Debug

Known issues

gotchaLoader chain ordering matters: preprocess-loader should run before other loaders (e.g., babel-loader) to avoid preprocessed comments being transpiled away.

fix

Place preprocess-loader earlier in the `use` array (right-to-left execution).

affects: >=0.0.0

gotchaDirectives inside @echo blocks may not be processed in coffee/shell type unless you apply a second preprocess pass after compilation.

fix

Chain two preprocess loaders: one with type:'cjsx' before CoffeeScript loader, one with type:'js' after.

affects: >=0.0.0

deprecatedWebpack 1 style `loaders` array with query strings is deprecated in Webpack 2+.

fix

Use `rules` with `use` array and `options` object.

affects: >=2.0.0

breakingUpgrade from v0.1.0 to v0.2.0 updated preprocess from v2 to v3, which may change behavior of some directives.

fix

Check preprocess v3 release notes for breaking changes; update your code if necessary.

affects: ~0.1.0

Errors

Common errors & fixes

Cannot find module 'preprocess-loader'

Missing npm install or not installed as devDependency.

fix

Run `npm install preprocess-loader --save-dev` or `yarn add preprocess-loader --dev`.

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema.

Using Webpack 2+ with the old `loaders` array instead of `rules`.

fix

Replace `module.loaders` with `module.rules` and `loader` with `use`.

Module build failed: Error: You may need an appropriate loader to handle this file type.

preprocess-loader is not in the loader chain or is placed after a loader that removes comments.

fix

Add preprocess-loader to the `use` array before other loaders (e.g., before babel-loader).

Upgrade

Version history

0.3.0latest on npm

Audit

Dependencies

preprocessrequiredCore dependency for text preprocessing (directives, conditionals).

webpackrequiredPeer dependency – loader operates within webpack's build system.

Agent activity

5 hits · last 30 days

node

Bingbot

Resources

githubhttps://github.com/dearrrfish/preprocess-loader ↗

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