JavaScript Constant Variables with Object.freeze();

constants.js

var CONST = {
    API_KEY: '123456789abcdefg',
    PI: 3.14
};
Object.freeze(CONST);

// Will print {API_KEY: "123456789abcdefg", PI: 3.14}
console.log(CONST);

// Attempt to change the value of PI to something else, but won't happen
CONST.PI = 2.2399;

// Attempt to add a new key to to the object
CONST.NEW_CONST = 'test';

// Will print the same {API_KEY: "123456789abcdefg", PI: 3.14}
console.log(CONST);