Sourcemaps with webpack css-loader

Question

I am struggling to get sourcemaps working with css-loader.

Output in console:

What the documentation from css-loader says:

SourceMaps

To include SourceMaps set the sourceMap query param.

require("css-loader?sourceMap!./file.css")

My webpack.config

var webpack = require('webpack')

module.exports = {
  entry: './src/client/js/App.js',

  output: {
    path: './public',
    filename: 'bundle.js',
    publicPath: '/'
  },

  plugins: process.env.NODE_ENV === 'production' ? [
    new webpack.optimize.DedupePlugin(),
    new webpack.optimize.OccurrenceOrderPlugin(),
    new webpack.optimize.UglifyJsPlugin()
  ] : [],

  module: {
    loaders: [
      { test: /\.js$/, exclude: /node_modules/, loader: 'babel-loader?presets[]=es2015&presets[]=react' },
      { test: /\.scss$/, loaders: ['style', 'css', 'sass']},
      { test: /\.css$/, loader: "style-loader!css-loader?sourceMap!./file.css" },
      { test: /\.png$/, loader: "url-loader?limit=100000" },
      { test: /\.jpg$/, loader: "file-loader" }
    ]
  }
}

How i include the sass

import React from 'react'
import { render } from 'react-dom'
import { Router, browserHistory } from 'react-router'
import routes from './routes'
import '../scss/main.scss'

render(
  <Router routes={routes} history={browserHistory}/>,
  document.getElementById('app')
)

Answer 1

1. Enable source-maps via webpack

   ...
   devtool: 'source-map'
   ...
   

2. You might want to enable source-maps for Sass-Files as well

   module: {
     loaders: [
       ...
       {
         test: /\.scss$/,
         loaders: [
           'style-loader',
           'css-loader?sourceMap',
           'sass-loader?sourceMap'
         ]
       }, {
         test: /\.css$/,
         loaders: [
           "style-loader",
           "css-loader?sourceMap"
         ]
       },
       ...
     ]
   }
   

3. Use extract text plugin to extract your css into a file.

   ...
   plugins: [
     ...
     new ExtractTextPlugin('file.css')
   ]
   ...
   

Answer 2

There are some properties you need to set in your webpack config.

{
   output: {
      ...
   },

   debug: true, // switches loaders into debug mode
   devtool: 'eval-cheap-module-source-map', // or one of the other flavors, not entirely sure if this is required for css source maps
   ...
}

The webpack dev server doesn't have debug on by default. Instead of setting it in your config, you can also pass the -d or --debug flag to webpack-dev-server via the CLI.