Consolidate ECMAScript version options

[jugglinmike]

Replace boolean options es3, es5, and esnext with a single option named esversion that may be set to 3, 5, or 6. This:

• precludes invalid configurations like es3: false, es5: true
• scales better for future versions of ECMAScript
• eliminates the ambiguity of esnext (whose meaning will change when ES6 is finalized)

This is definitely a breaking change and should be implemented for the next major release of JSHint (if at all).

[nicolo-ribaudo]

Related / duplicated -> #1148

[nicolo-ribaudo]

I'm implementing this option without removing es3, es5 and esnext.

I've two questions:

1. What does es5: false mean? Is it totally unuseful?
2. Should esversion: 2015 be a possible value? (synonymous of esversion: 6)

[lukeapage]

IMO

1. i think so.. depends what you mean, I assume es5: false, es3: true => esversion: 3, es5: false, esnext:true => Invalid option ?
2. yes! good thinking.

[nicolo-ribaudo]

esversion: 3, es5: false, esnext:true => Invalid option ?

If JSHint throws an Invalid option warning fot that code, it also should throw it for esnext: true, es3: true, but this would be a breaking change. I think JSHint should silently ignore this invalid configuration ad consider only the last option:

• esnext: true, es3: true = esversion: 3
• esversion: 3, es5: false, esnext:true = esversion: 6

i think so.. depends what you mean

I meant this:

// jshint es5: false

var x = {
  get a() {} // es5 syntax, but jshint doesn't warn
};

[Mouvedia]

Couldn't esnext: true become an alias of esversion: 6+?