The parentheses-less javascript dialect in the title of this HN article relies on ES6 and uses 6 characters:

    !+[]`$

The parent link above is ES5 and uses 8 characters:

    !+[](){}

The jsfuck.com ES6 dialect uses 6 characters:

    !+[]()

jsfuck was previously ES5 but they now rely on ES6isms to shorten their code.