- six basic types of values in JavaScript: numbers (64 bits), strings, Booleans, objects, functions, and undefined
- % - reminder
- Infinity, - Infinity, NaN (0 / 0, Infinity - Infinity...)
- typeof (typeof 4.5, typeof "x")
- console.log(NaN == NaN) // → false
- null and undefined
- 0, NaN, and the empty string ("") count as false, while all the other values count as true
console.log(8 * null)
// → 0
console.log("5" - 1)
// → 4
console.log("5" + 1)
// → 51
console.log("five" * 2)
// → NaN
console.log(false == 0)
// → true
console.log(null == undefined);
// → true
console.log(null == 0);
// → false