PhpStorm "Let definition are not supported by current JavaScript version"

Question

I am trying to be a good little programmer and use the new tools available for coding JavaScript. Therefore I'm trying to use let instead of var to isolate variables.

This works fine in my browser however PhpStorm sees it as an error and when I hover above it gives me:

Let definition are not supported by current JavaScript version

So my question is how do I upgrade the current JavaScript version?

Answer 1

Go to

Settings / Languages & Frameworks / JavaScript

(it may be Preferences / Languages & Frameworks / JavaScript on some OSes)

...and set the "JavaScript language version" to "ECMAScript 6" (or, if they've updated to reflect current naming, "ECMAScript 2015" — or "ECMAScript 2016" or later if you're coding to a newer spec):

Answer 2

The setting is found in File -> Settings -> Language & Frameworks -> Javascript and the option should be on the left, a dropdown box next to "JavaScript Language Version"