Interesting, I've found the reverse is true for me with ES6.

For example, ES6 already had local functions (and a very terse form of that too using lambdas)

  class C {
    method() {
      let localFunction = x => x + 1
      function anotherLocal(a) { return a + 1; }
    }
  }

... arrays are normally used to represent tuples (or freeform objects), and it includes destructuring too:

  function f(x) { return [x, x*2] }
  let [x, xdoubled] = f(5)

or

  function f(y) { return {y, timesTwo: y*2} }
  let {y, timesTwo} = f(10)

It almost seemed to me that many of the features listed here were "borrowed" from the liberal style allowed by ES6 and TypeScript (am probably wrong, and both are borrowing from elsewhere).