Enumerations (Object.freeze) ¶

Description ¶

There’s no native enumeration type in pure JavaScript, but you can use the enum type in TypeScript or emulate one with something similar to this:

           const Sauce = Object.freeze({
  BBQ: Symbol('bbq'),
  CHILI: Symbol('chili'),
  GARLIC: Symbol('garlic'),
  KETCHUP: Symbol('ketchup'),
  MUSTARD: Symbol('mustard')
});

          

Freezing an object prevents you from adding or removing its attributes .

This is different from a constant, which can be mutable !

A constant will always point to the same object, but the object itself might change its value:

           > const fruits = ['apple', 'banana'];
> fruits.push('orange'); // ['apple', 'banana', 'orange']

           > fruits = [];

          

           TypeError: Assignment to constant variable.

          

You can add an orange to the array, which is mutable, but you can’t modify the constant that is pointing to it.