types_and_grammar_ch2_6.js

function foo() {
	var undefined = 2;
	console.log(undefined); // 2
}
foo();

// In strict mode, this is also valid
function foo() {
	'use strict';
	var undefined = 2;
	console.log(undefined); // 2
}
foo();

// However, you cannot overwrite the global undefined
// At least in Google Chrome Console
var undefined = 2;
console.log(undefined); // undefined