Where are you finding that? This is what I get from Chrome: foo(1, 2, 3) // ["a", "b", "c"] // [1, 2, 3] And this is what I get from https://babe

Where are you finding that? This is what I get from Chrome: foo(1, 2, 3) // ["a", "b", "c"] // [1, 2, 3] And this is what I get from https://babel.io/repl https://babel.io/repl : 'use strict'; function foo() { var _arguments = arguments; var bar = function bar() { for (var _len = arguments.length, abc = Array(_len), _key = 0; _key < _len; _key++) { abc[_key] = arguments[_key]; } console.log(abc); console.log(_arguments); }; bar('a', 'b', 'c'); }