Webpack Config Validator#

Validate webpack configuration files exported as JSON for structural correctness, entry/output issues, deprecated loaders and plugins, optimization configuration, and best practices. Pure Python 3 stdlib — no external dependencies.

Note: webpack configs are JS/TS, not directly parseable. This validator works with JSON-exported configs. Export via:

bash

node -e "console.log(JSON.stringify(require('./webpack.config.js')))" > config.json
python3 scripts/webpack_config_validator.py validate config.json

Commands#

validate — Full validation with all rules#

bash

python3 scripts/webpack_config_validator.py validate config.json
python3 scripts/webpack_config_validator.py validate config.json --strict
python3 scripts/webpack_config_validator.py validate config.json --format json --mode production

check — Quick check (errors and warnings only)#

bash

python3 scripts/webpack_config_validator.py check config.json
python3 scripts/webpack_config_validator.py check config.json --format summary

explain — Show all rules with descriptions#

bash

python3 scripts/webpack_config_validator.py explain config.json
python3 scripts/webpack_config_validator.py explain config.json --format json

suggest — Run validation and propose fixes#

bash

python3 scripts/webpack_config_validator.py suggest config.json
python3 scripts/webpack_config_validator.py suggest config.json --format json

Flags#

FlagDescription--strictTreat warnings as errors — exit code 1 (CI-friendly)--format textHuman-readable output (default)--format jsonMachine-readable JSON--format summaryCompact summary with counts--mode productionOverride mode context for mode-specific rules (E3, O3)--mode developmentOverride mode context for mode-specific rules

Validation Rules (24)#

Structure (5)#

RuleSeverityDescriptionS1errorFile not found or unreadableS2errorEmpty config fileS3errorInvalid JSON syntaxS4errorMissing required fields (entry, output)S5warning/infoUnknown or deprecated top-level keys

Entry/Output (4)#

RuleSeverityDescriptionE1errorEmpty entry point (empty string, object, or array)E2errorOutput section missing 'path' propertyE3warningOutput filename without content hash in production modeE4warningpublicPath not set

Module/Rules (4)#

RuleSeverityDescriptionM1warningModule rule without 'test' patternM2warningDuplicate loader for same test patternM3warningDeprecated loaders (raw-loader, url-loader, file-loader, json-loader)M4infoNo babel-loader/ts-loader/esbuild-loader/swc-loader for JS/TS

Plugins (4)#

RuleSeverityDescriptionP1errorDeprecated plugins (UglifyJsPlugin, ExtractTextPlugin, CommonsChunkPlugin)P2warningDuplicate plugin instancesP3infoHtmlWebpackPlugin without explicit templateP4warningMiniCssExtractPlugin without corresponding loader in rules

Optimization (3)#

RuleSeverityDescriptionO1infoMissing splitChunks configurationO2infoMissing custom minimizer configurationO3warning/infodevtool set to eval or source-map in production mode

Best Practices (4)#

RuleSeverityDescriptionB1infoMissing resolve.extensionsB2warningHardcoded absolute filesystem paths in configB3warningNo mode set (development/production/none)B4infoMissing devServer configuration

Exit Codes#

CodeMeaning0No errors (warnings allowed unless --strict)1Errors found (or warnings in --strict mode)2File not found / parse error

CI Integration#

yaml

# GitHub Actions example
- name: Validate webpack config
  run: |
    node -e "console.log(JSON.stringify(require('./webpack.config.js')))" > /tmp/wp-config.json
    python3 scripts/webpack_config_validator.py validate /tmp/wp-config.json --strict --mode production --format json

Example Output#

text

webpack.config validate — config.json
======================================
[ERROR  ] S4: Missing required top-level field(s): output
         Every webpack config needs at least 'entry' and 'output'.
[WARNING] E4: output.publicPath not set
         Set publicPath to ensure assets are loaded from the correct URL. Common values: '/', '/assets/', 'auto'.
[WARNING] M3: Deprecated loader 'file-loader' in rule 2
         Replace with asset/resource (webpack 5 built-in).
[ERROR  ] P1: Deprecated plugin 'UglifyJsPlugin' at index 0
         Replace with TerserPlugin (terser-webpack-plugin).
[INFO   ] O1: No optimization.splitChunks configuration
         splitChunks enables automatic code splitting for shared dependencies. Add optimization: { splitChunks: { chunks: 'all' } } for better caching.
[WARNING] B3: No 'mode' set (development/production/none)
         Set mode to enable webpack's built-in optimizations. Without mode, webpack defaults to 'production' with a warning.

Result: INVALID
Summary: 2 error(s), 3 warning(s), 1 info