UglifyJS issues

[iongion]

I am using fs-extra which uses universalify, now there is a problem when using uglifyjs as it does not know arrow functions, can you change the module not to use arrow functions ?

The scenario is this:

I deploy NodeJS server side apps, bundled in a single file(executing in AWS lambda env).
As you know, webpack usually has an ignore option when transpiling and in the most common cases node_modules is what is ignored.

Now, after webpack transpiles the code it will post processes it using UglifyJS and there, UglifyJS gets stuck as it cannot minify arrow functions:

'use strict'

exports.fromCallback = function (fn) {
  return Object.defineProperty(function () {
    if (typeof arguments[arguments.length - 1] === 'function') fn.apply(this, arguments)
    else {
      return new Promise(function (resolve, reject) {
        arguments[arguments.length] = function(err, res) {
          if (err) return reject(err)
          resolve(res)
        }
        arguments.length++
        fn.apply(this, arguments)
      })
    }
  }, 'name', { value: fn.name })
}

exports.fromPromise = function (fn) {
  return Object.defineProperty(function () {
    const cb = arguments[arguments.length - 1]
    if (typeof cb !== 'function') return fn.apply(this, arguments)
    else fn.apply(this, arguments).then(function(r) {
      cb(null, r);
    }).catch(cb)
  }, 'name', { value: fn.name })
}

[RyanZim]

fs-extra (and universalify) only support Node 4+ which supports arrow functions just fine. fs-extra uses them as well. We're not going to revert just to support outdated tooling.

You need to use the es branch of UglifyJS: https://www.npmjs.com/package/uglify-es

CC: @jprichardson

[jprichardson]

@iongion I don't understand why you'd uglify your own code in a server environment.

[vinaynb]

@jprichardson any tips on what if the use case is using this package in a electron app after uglifying it ?

[vinaynb]

@RyanZim i understand your point of not reverting the code but can we just add a engines property to package.json explicitly declaring minimum node version required by plugin. Doing this will help people like me who can use babel-engine-plugin and transpile such modules using babel.

[RyanZim]

The real solution is to use https://www.npmjs.com/package/uglify-es. That said, I'm not opposed to adding engines to the package.json. PR welcome.