Question

Caches the result of following loaders on disk (default) or in the database

安装

npm install --save-dev cache-loader

用法

在一些性能开销较大的 loader 之前添加此 loader，以将结果缓存到磁盘里。

webpack.config.js

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

⚠️ 请注意，保存和读取这些缓存文件会有一些时间开销，所以请只对性能开销较大的 loader 使用此 loader。

Options

Name	Type	Default	Description
cacheKey	{Function(options, request) -> {String}}	undefined	Allows you to override default cache key generator
cacheDirectory	{String}	path.resolve('.cache-loader')	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)
write	{Function(cacheKey, data, callback) -> {void}}	undefined	Allows you to override default write cache data to file (e.g. Redis, memcached)
read	{Function(cacheKey, callback) -> {void}}	undefined	Allows you to override default read cache data from file

示例

webpack.config.js

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

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')
      }
    ]
  }
}