Inserting a function in Webpack Plugin

Question

Does anyone know how to insert and reuse a function in a Webpack plugin? Like from my plugin insert that function myFunction() and call it from the generated bundle?

Background information:

I'm replacing some paths to some assets that are inside other libraries.

• Library A uses file1.afm to file14.afm
• Library B uses file1.trie to file4.trie

I put these files in my package using file-loader and then I require each file:

const f1 = require('file1.afm') 

And so forth for every single file.

But Library A and B are doing something like the following:

data = base64.toByteArray(fs.readFileSync('../src/js/somePath/inLibrary/Private/file1.afm', 'base64'));

For every single file. I want to replace that path with the correct path to the bundle, but the __dirname doesn't help. That's why I want to use callsites.

What I want to do is insert callsites as a global dependency on my bundle and use it similarly to __webpack_require__(moduleId) so that I can pull in the executing js file path (__dirname or __filename don't work)

So in theory I would insert callsites()[0].getFileName() + __webpack_require__(moduleId)

So far my config looks like this, and webpack-file-resolver is the current plugin i'm doing:

const path = require('path')
const webpackTs = require('webpack-config-typescript')
var WebpackFileResolver = require('webpack-file-resolver')


let config = {
  entry: path.join(__dirname, 'src/handler.ts'),
  target: 'node',
  output: {
    filename: 'deploy/handler_[hash].js',
    libraryTarget: 'commonjs',
    path: path.join(__dirname)
  }
}

config = webpackTs.ts(config)
config.module.rules.push({
  test: /\.(ttf|trie|afm)$/,
  loader: "file-loader",
  options: {
    name: "[name].[ext]",
    outputPath: "deploy",
    publicPath: "./"
  },
})

config.plugins.push(new WebpackFileResolver({
  test: /\.(trie|afm)$/,
  serverPath: "./"
}))

module.exports = config 

So far this is what I got:

const ConcatSource = require("webpack-sources").ConcatSource

function getRequires (options, chunks) {
  return chunks.reduce((c, chunk) => {
    chunk.forEachModule((module) => {
      const deps = module && module.fileDependencies && module.fileDependencies || []
      deps.forEach((filepath) => {
        if(options.test.test(filepath)) {
          c.add({
            path: filepath,
            id: module.id
          })
        }
      })
    })
    return c
  }, new Set())
}

class WebpackFileResolverPlugin {
  constructor(options = {}) {
    this.options = options
  }

  apply(compiler) {
    const options = this.options
    compiler.plugin('compilation', (compilation) => {
      compilation.plugin('optimize-chunk-assets',  (chunks, done) => {
        const requires = getRequires(options, chunks)
        replaceBundleReadDir(compilation, chunks, requires)
        done()
      })
    })
  }
}

function replaceBundleReadDir(compilation, chunks, requires){
    chunks.forEach(function (chunk) {
        chunk.files.forEach(function (fileName) {
            replaceSource(compilation, fileName, requires)
        })
    })
}

function replaceSource(compilation, fileName, requires){
    let result = compilation.assets[fileName].source()
  const source = []
    requires.forEach((require) => {
    let buffer = []
    for (let c of result) {
      if (c !== '\n') {
        buffer.push(c)
      } else {
        const line = buffer.join('')
        const newLine = replaceFsReadDir (require, line)
        if (newLine !== undefined) {
          result = result.replace(line, newLine)
        }
        buffer = []
      }
    }
    })
    compilation.assets[fileName] = new ConcatSource(result)
}

function replaceFsReadDir (require, line) {
  const webpackRequire = '__webpack_require__'
  const fileName = require.path.replace(/^.*[\\\/]/, '')
  const fileStartMarker = line.indexOf(fileName)
  const readDirMarker = line.lastIndexOf('readFile')
  if (fileStartMarker !== -1 && readDirMarker !== -1) {
    let fileEndMarker = line.indexOf(')', fileStartMarker)
    let getEnd = line.slice(fileStartMarker, fileEndMarker + 1)
    fileEndMarker = (getEnd.length > fileName.length + 2) ? line.indexOf(',', fileStartMarker) : fileEndMarker
    const startSlice = line.indexOf('(', readDirMarker) + 1
    const newLine = `${line.slice(0, startSlice)}${webpackRequire}(${require.id})${line.slice(fileEndMarker)}`
    return newLine
  } else {
    return undefined
  }
}

module.exports = WebpackFileResolverPlugin

Answer 1

In the meantime I'll use the following, it's very hacky so I can't really recommend it.

What I do is I prepend my global functions to my bundle, then replace the paths with path to the current executing javascript. Any thoughts would be appreciated.

const ConcatSource = require("webpack-sources").ConcatSource

// This is the function I want to use on my bundle
const noRestForTheWicked = `
const __callsites__ = () => {
    const _ = Error.prepareStackTrace;
    Error.prepareStackTrace = (_, stack) => stack;
    const stack = new Error().stack.slice(1);
    Error.prepareStackTrace = _;
    return stack;
}
const __current_file__ = () => {
  const sep = require('path').sep
  let filePieces = __callsites__()[0].getFileName().split(sep)
  return filePieces.slice(0, -1).join(sep) + sep
};

`

function getRequires (options, chunks) {
  return chunks.reduce((c, chunk) => {
    chunk.forEachModule((module) => {
      const deps = module && module.fileDependencies && module.fileDependencies || []
      deps.forEach((filepath) => {
        if(options.test.test(filepath)) {
          c.add({
            path: filepath,
            id: module.id
          })
        }
      })
    })
    return c
  }, new Set())
}

class WebpackFileResolverPlugin {
  constructor(options = {}) {
    this.options = options
  }

  apply(compiler) {
    const options = this.options
    compiler.plugin('compilation', (compilation) => {
      compilation.plugin('optimize-chunk-assets',  (chunks, done) => {
        const requires = getRequires(options, chunks)
        replaceBundleReadDir(compilation, chunks, requires, options)
        done()
      })
    })
  }
}

function replaceBundleReadDir(compilation, chunks, requires, options){
    chunks.forEach(function (chunk) {
        chunk.files.forEach(function (fileName) {
            replaceSource(compilation, fileName, requires, options)
        })
    })
}

function replaceSource(compilation, fileName, requires, options){
    let result = compilation.assets[fileName].source()
  if ('serverPath' in options && options.serverPath !== undefined) {
     // This is where the hacking happens
     result = noRestForTheWicked + result
  }
    requires.forEach((require) => {
    let buffer = []
    for (let c of result) {
      if (c !== '\n') {
        buffer.push(c)
      } else {
        const line = buffer.join('')
        const newLine = replaceFsReadDir (require, line, options)
        if (newLine !== undefined) {
          result = result.replace(line, newLine)
        }
        buffer = []
      }
    }
    })
    compilation.assets[fileName] = new ConcatSource(result)
}

function replaceFsReadDir (require, line, options) {
  const webpackRequire = '__webpack_require__'
  const fileName = require.path.replace(/^.*[\\\/]/, '')
  const fileStartMarker = line.indexOf(fileName)
  const readDirMarker = line.lastIndexOf('readFile')
  if (fileStartMarker !== -1 && readDirMarker !== -1) {
    let fileEndMarker = line.indexOf(')', fileStartMarker)
    let getEnd = line.slice(fileStartMarker, fileEndMarker + 1)
    fileEndMarker = (getEnd.length > fileName.length + 2) ? line.indexOf(',', fileStartMarker) : fileEndMarker
    const startSlice = line.indexOf('(', readDirMarker) + 1
    let importStr = `${webpackRequire}(${require.id})`
    if ('serverPath' in options && options.serverPath !== undefined) {
      // Server Land, brace for impact, inserting the thing
      importStr = `__current_file__() + ${importStr}`
    }
    const newLine = `${line.slice(0, startSlice)}${importStr}${line.slice(fileEndMarker)}`
    return newLine
  } else {
    return undefined
  }
}

module.exports = WebpackFileResolverPlugin