Why does JSHint throw a warning if I am using const?

This is the error I get when using const:

<error line="2" column="1" severity="warning" message="&apos;const&apos; is available in ES6 (use esnext option) or Mozilla JS extensions (use moz)." source="jshint.W104" />

My code looks like this:

const Suites = {
    Spade: 1,
    Heart: 2,
    Diamond: 3,
    Club: 4
};

The code works fine only JSHint is warning me every time.