"error 'Set' is not defined no-undef" in ecmaVersion 2017

Tell us about your environment

• ESLint Version: └─┬ gulp-eslint@3.0.1 └── eslint@3.12.2

• Node Version: v4.2.6

• npm Version: npm: ‘3.5.2’

What parser (default, Babel-ESLint, etc.) are you using?

gulp-eslint

Please show your full configuration:

env:
  browser: true                       # Enable Browser global variables

parserOptions:
  ecmaVersion: 2017                   # Validate ECMAScript 2016 features
  sourceType: module                  # Allow ECMAScript modules

globals:
  PIXI: false
  Phaser: false

extends: 'eslint:recommended'

rules:
  indent: [2, 2]                      # Indent code with 2 spaces
  quotes: [2, single]                 # Use single quotes for strings
  linebreak-style: [2, unix]          # Favor Unix-style line endings
  semi: [2, always]                   # End lines with semicolons

What did you do? Please include the actual source code causing the issue.

  static getLockedBirds(game){
    var allBirdIds=new Set();
    for(let i=0;i<=game.animationInfo.maxBirdFrame;i++){
      allBirdIds.add(i);
    }

    var unlockedBirds = new Set(DataAccess.getConfig('unlockedBirdSprites'));
    var lockedBirds = [...allBirdIds].filter(x => !unlockedBirds.has(x)); //find all bird ids that are not in the unlocked set but ARE in the allBird set

    return lockedBirds;
  }

What did you expect to happen? Set is a ECMA 2015 object. By using ECMA 8/2017 I expected the parser to recognize this. If I add es6: true to the environment configuration, no error is thrown

What actually happened? Please include the actual, raw output from ESLint.

/home/james/Documents/birdu/src/objects/Helpers/DataAccess.js
  31:24  error  'Set' is not defined  no-undef
  36:29  error  'Set' is not defined  no-undef

[not-an-aardvark]

Hi, thanks for the report.

The parserOptions config only handles options for the parser (e.g. if you’re using ES6 syntax). However, it doesn’t affect the list of availale globals, which is used by rules like no-undef. To set ES6 globals, you should add env: {es6: true} to your config (as you mentioned you did).

[platinumazure]

Agreed, for some reason I thought we mentioned ecmaVersion but you are right, it links to the Configuring page.

I’d like to see a paragraph on the difference between ecmaVersion (syntax) and envs (globals), yeah.