babel-plugin-const-enum

babel-plugin-const-enum

Transform TypeScript const enums

Install

Using npm:

npm install --save-dev babel-plugin-const-enum

or using yarn:

yarn add babel-plugin-const-enum --dev

Usage

removeConst (default)

Removes the const keyword to use regular enum. Can be used in a slower dev build to allow const, while prod still uses tsc. See babel#6476.

// Before:
const enum MyEnum {
  A = 1,
  B = A,
  C,
  D = C,
  E = 1,
  F,
  G = A * E,
  H = A ** B ** C,
  I = A << 20
}

// After:
enum MyEnum {
  A = 1,
  B = A,
  C,
  D = C,
  E = 1,
  F,
  G = A * E,
  H = A ** B ** C,
  I = A << 20
}

.babelrc

{
  "plugins": [
    "const-enum"
  ]
}

Or Explicitly:

.babelrc

{
  "plugins": [
    [
      "const-enum",
      {
        "transform": "removeConst"
      }
    ]
  ]
}

constObject

Transforms into a const object literal. Can be further compressed using Uglify/Terser to inline enum access. See babel#8741.

// Before:
const enum MyEnum {
  A = 1,
  B = A,
  C,
  D = C,
  E = 1,
  F,
  G = A * E,
  H = A ** B ** C,
  I = A << 20
}

// After:
const MyEnum = {
  A: 1,
  B: 1,
  C: 2,
  D: 2,
  E: 1,
  F: 2,
  G: 1,
  H: 1,
  I: 1048576
};

.babelrc

{
  "plugins": [
    [
      "const-enum",
      {
        "transform": "constObject"
      }
    ]
  ]
}