variables
let variable = value
let user = 'John', age = 25, message = 'Hello';
constants
const constant = value
const myBirthday = '18.04.1982';
There is a widespread practice to use constants as aliases for difficult-to-remember values that are known prior to execution. .. const COLOR_RED = "#F00"; const COLOR_GREEN = "#0F0";
let n = 123;
n = 12.345;
NaN represents a computational error