Arrow Functions: No arguments object, since arrow functions have no arguments binding, you must rely on named and rest parameters to access function arguments.

new.js

//ES2015
var foo = (x,y) => arguments[0];
foo("lee","2") //ReferenceError: arguments is not defined [Learn More]

old.js

//ES5
var foo = function (x,y) { return arguments[0]; }
foo("lee", "2"); //returns "lee";