webpack css-loader: fails to load a png file referenced as url('path') inside a css file

问题

I am making my first steps in using webpack...so far not very successful. In my .css file, there is a image background defined with a url:

background-image: url("patterns/header-profile.png");

The app spectacularly craches on launch with this error:

ERROR in ./~/css-loader?"modules":true,"sourceMap":true,"importLoaders":1,"localIdentName":"[local]__[hash:base64:5]"}!./~/postcss-loader!./src/assets/css/in
spinia.css

Module not found: Error: Can't resolve 'patterns/header-profile.png' in 'C:\----  absolute path  ---\src\assets\css'

First of all this is my project structure:

./src/
  --> assets
        --> patterns
              --> header-profile.png
        --> mystyle.css  // <-- sos: this is where background img is defined
--> index.html
--> index.tsx

Second this is my webpack.config.json:

var webpack = require('webpack');
var path = require('path');

// variables
var isProduction = process.argv.indexOf('-p') >= 0;
var sourcePath = path.join(__dirname, './src');
var outPath = path.join(__dirname, './dist');

// plugins
var HtmlWebpackPlugin = require('html-webpack-plugin');
var ExtractTextPlugin = require('extract-text-webpack-plugin');

module.exports = {
  context: sourcePath,
  entry: {
    main: './index.tsx',
    vendor: [
      'react',
      'react-dom',
      'react-redux',
      'react-router',
      'react-router-redux',
      'redux'
    ]
  },
  output: {
    path: outPath,
    publicPath: './',
    filename: 'bundle.js',
  },
  target: 'web',
  resolve: {
    extensions: ['.js', '.ts', '.tsx'],
    // Fix webpack's default behavior to not load packages with jsnext:main module
    // https://github.com/Microsoft/TypeScript/issues/11677 
    mainFields: ['main']
  },
  module: {
    loaders: [
      // .ts, .tsx
      {
        test: /\.tsx?$/,
        loader: isProduction
          ? 'awesome-typescript-loader?module=es6'
          : [
            'react-hot-loader',
            'awesome-typescript-loader'
          ]
      },
      // css 
      {
        test: /\.css$/,
        loader: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          publicPath: './',
          loader: [
            {
              loader: 'css-loader',
              query: {
                modules: true,
                sourceMap: !isProduction,
                importLoaders: 1,
                localIdentName: '[local]__[hash:base64:5]'
              }
            },
            {
              loader: 'postcss-loader'
            }
          ]
        })
      },
      // static assets 
      { test: /\.html$/, loader: 'html-loader' },
      { test: /\.png$/, loader: "url-loader?limit=10000" },
      { test: /\.jpg$/, loader:  'file-loader' },
    ],
  },
  plugins: [
    new webpack.LoaderOptionsPlugin({
      options: {
        context: sourcePath,
        postcss: [
          require('postcss-import')({ addDependencyTo: webpack }),
          require('postcss-url')(),
          require('postcss-cssnext')(),
          require('postcss-reporter')(),
          require('postcss-browser-reporter')({ disabled: isProduction }),
        ]
      }
    }),
    new webpack.optimize.CommonsChunkPlugin({
      name: 'vendor',
      filename: 'vendor.bundle.js',
      minChunks: Infinity
    }),
    new webpack.optimize.AggressiveMergingPlugin(),
    new ExtractTextPlugin({
      filename: 'styles.css',
      disable: !isProduction
    }),
    new HtmlWebpackPlugin({
      template: 'index.html'
    })
  ],
  devServer: {
    contentBase: sourcePath,
    hot: true,
    stats: {
      warnings: false
    },
  },
  node: {
    // workaround for webpack-dev-server issue 
    // https://github.com/webpack/webpack-dev-server/issues/60#issuecomment-103411179
    fs: 'empty',
    net: 'empty'
  }
};

And finally this is the way I require mystyle.css in the index js file:

require('/assets/css/inspinia.css');

I have looked around stackoverflow, github and google. I saw that other people have faced similar problems. But I don't understand the various solutions they applied (I am new to webpack).

Any help would be greatly appreciated.

回答1:

This is the way I fixed this problem without really understanding why it solved my problem (just changing properties around...).

First of all on my webpack.config.json file I made sure that this publicPath is absolute ('/') and not relative ('./')

{
  output:{
     publicPath: '/'
  }
}

Second, in my index.tsx where I require mystyle.css, I made sure that it is relative path:

require('./assets/css/mystyle.css')

And finally inside mystyle.css where I reference my images, I made sure that it is absolute path (...crazy...). So for example, I would have:

background: url("/patterns/header-profile.png")

And it magically works!

Could someone explain what is logic behind this configuration, it would help me a long way to understand how webpack works especially when it comes to css files, images resources and absolute/relative paths.

来源：https://stackoverflow.com/questions/42351593/webpack-css-loader-fails-to-load-a-png-file-referenced-as-urlpath-inside-a

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url

Webpack

png

css-loader