cache-loader

The cache-loader allow to Caches the result of following loaders on disk (default) or in the database.

Getting Started

To begin, you'll need to install cache-loader:

npm install --save-dev cache-loader

Add this loader in front of other (expensive) loaders to cache the result on disk.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.ext$/,
        use: ['cache-loader', ...loaders],
        include: path.resolve('src'),
      },
    ],
  },
};

⚠️ Note that there is an overhead for saving the reading and saving the cache file, so only use this loader to cache expensive loaders.

Options

Name	Type	n Default	Description
cacheContext	{String}	undefined	Allows you to override the default cache context in order to generate the cache relatively to a path. By default it will use absolute paths
cacheKey	{Function(options, request) -> {String}}	undefined	Allows you to override default cache key generator
cacheDirectory	{String}	findCacheDir({ name: 'cache-loader' }) or os.tmpdir()	Provide a cache directory where cache items should be stored (used for default read/write implementation)
cacheIdentifier	{String}	cache-loader:{version} {process.env.NODE_ENV}	Provide an invalidation identifier which is used to generate the hashes. You can use it for extra dependencies of loaders (used for default read/write implementation)
compare	{Function(stats, dep) -> {Boolean}}	undefined	Allows you to override default comparison function between the cached dependency and the one is being read. Return true to use the cached resource
precision	{Number}	0	Round mtime by this number of milliseconds both for stats and dep before passing those params to the comparing function
read	{Function(cacheKey, callback) -> {void}}	undefined	Allows you to override default read cache data from file
readOnly	{Boolean}	false	Allows you to override default value and make the cache read only (useful for some environments where you don't want the cache to be updated, only read from it)
write	{Function(cacheKey, data, callback) -> {void}}	undefined	Allows you to override default write cache data to file (e.g. Redis, memcached)

Examples

Basic

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        use: ['cache-loader', 'babel-loader'],
        include: path.resolve('src'),
      },
    ],
  },
};

Database Integration

webpack.config.js

// Or different database client - memcached, mongodb, ...
const redis = require('redis');
const crypto = require('crypto');

// ...
// connect to client
// ...

const BUILD_CACHE_TIMEOUT = 24 * 3600; // 1 day

function digest(str) {
  return crypto
    .createHash('md5')
    .update(str)
    .digest('hex');
}

// Generate own cache key
function cacheKey(options, request) {
  return `build:cache:${digest(request)}`;
}

// Read data from database and parse them
function read(key, callback) {
  client.get(key, (err, result) => {
    if (err) {
      return callback(err);
    }

    if (!result) {
      return callback(new Error(`Key ${key} not found`));
    }

    try {
      let data = JSON.parse(result);
      callback(null, data);
    } catch (e) {
      callback(e);
    }
  });
}

// Write data to database under cacheKey
function write(key, data, callback) {
  client.set(key, JSON.stringify(data), 'EX', BUILD_CACHE_TIMEOUT, callback);
}

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        use: [
          {
            loader: 'cache-loader',
            options: {
              cacheKey,
              read,
              write,
            },
          },
          'babel-loader',
        ],
        include: path.resolve('src'),
      },
    ],
  },
};

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT