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Cover image for This SUPERIOR way ov defining enums in JavaScript!
Calin Baenen
Calin Baenen

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This SUPERIOR way ov defining enums in JavaScript!

#javascript #webdev

The Standard Way ov Defining An Enum

In JavaScript, the standard way to define an enum – according to the TypeScript compiler – is:

"use strict";
var Fruit;
(function (Fruit) {
  Fruit[Fruit["BANANA"] = 0] = "BANANA";
  Fruit[Fruit["ORANGE"] = 1] = "ORANGE";
  Fruit[Fruit["APPLE"]  = 2] = "APPLE";
})(Fruit || (Fruit = {}));
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Or, if we strip the (unnecessary) mapping from number to string, we can do:

"use strict";
var Fruit = {
  "BANANA": 0,
  "ORANGE": 1,
  "APPLE":  2
};
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The Better Way ov Defining An Enum

... However, there is a better way to define an enum – and the method will ensure:

  1. the enum values are unique,
  2. the values can't be overriden,
  3. the definition is hoisted. 
var Fruit;
{
  Fruit = Object.defineProperties((Fruit = Object.create(null)), {
    BANANA: {writable: false,  value: Symbol("BANANA")},
    ORANGE: {writable: false,  value: Symbol("ORANGE")},
    APPLE:  {writable: false,  value: Symbol("APPLE")}
  });
}
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