This a weird behaviour, i've tested on Chrome and works just fine without any flag, but in node it doesn't work event with the latest version
$ node --harmony_destructuring app.js
[length, offset] = this.getint(data, offset, 2)
ReferenceError: Invalid left-hand side in assignment
$ node -v
The correct syntax would be
const iterable = ['a', 'b']; const [x, y] = iterable;
You can read more on destructuring here.