index.js

const path = require('path')

module.exports = (api, projectOptions) => {
  const useThreads = process.env.NODE_ENV === 'production' && !!projectOptions.parallel

  const { semver, loadModule } = require('@vue/cli-shared-utils')
  const vue = loadModule('vue', api.service.context)
  const isVue3 = (vue && semver.major(vue.version) === 3)

  api.chainWebpack(config => {
    config.resolveLoader.modules.prepend(path.join(__dirname, 'node_modules'))

    if (!projectOptions.pages) {
      config.entry('app')
        .clear()
        .add('./src/main.ts')
    }

    config.resolve
      .extensions
        .prepend('.ts')
        .prepend('.tsx')

    const tsRule = config.module.rule('ts').test(/\.ts$/)
    const tsxRule = config.module.rule('tsx').test(/\.tsx$/)

    // add a loader to both *.ts & vue<lang="ts">
    const addLoader = ({ name, loader, options }) => {
      tsRule.use(name).loader(loader).options(options)
      tsxRule.use(name).loader(loader).options(options)
    }

    addLoader({
      name: 'cache-loader',
      loader: require.resolve('cache-loader'),
      options: api.genCacheConfig('ts-loader', {
        'ts-loader': require('ts-loader/package.json').version,
        'typescript': require('typescript/package.json').version,
        modern: !!process.env.VUE_CLI_MODERN_BUILD
      }, 'tsconfig.json')
    })

    if (useThreads) {
      addLoader({
        name: 'thread-loader',
        loader: require.resolve('thread-loader'),
        options:
          typeof projectOptions.parallel === 'number'
            ? { workers: projectOptions.parallel }
            : {}
      })
    }

    if (api.hasPlugin('babel')) {
      addLoader({
        name: 'babel-loader',
        loader: require.resolve('babel-loader')
      })
    }
    addLoader({
      name: 'ts-loader',
      loader: require.resolve('ts-loader'),
      options: {
        transpileOnly: true,
        appendTsSuffixTo: ['\\.vue$'],
        // https://github.com/TypeStrong/ts-loader#happypackmode-boolean-defaultfalse
        happyPackMode: useThreads
      }
    })
    // make sure to append TSX suffix
    tsxRule.use('ts-loader').loader(require.resolve('ts-loader')).tap(options => {
      options = Object.assign({}, options)
      delete options.appendTsSuffixTo
      options.appendTsxSuffixTo = ['\\.vue$']
      return options
    })

    // this plugin does not play well with jest + cypress setup (tsPluginE2e.spec.js) somehow
    // so temporarily disabled for vue-cli tests
    if (!process.env.VUE_CLI_TEST) {
      config
        .plugin('fork-ts-checker')
        .use(require('fork-ts-checker-webpack-plugin'), [{
          typescript: {
            extensions: {
              vue: {
                enabled: true,
                compiler: isVue3 ? require.resolve('@vue/compiler-sfc') : require.resolve('vue-template-compiler')
              }
            },
            diagnosticOptions: {
              semantic: true,
              // https://github.com/TypeStrong/ts-loader#happypackmode
              syntactic: useThreads
            }
          }
        }])
    }
  })
}