Speeding Up Enum

Setting enum as const to increase speed

enum can be set as a constant to speed up the performance. This way, during execution, instead of referencing the function generated by TypeScript to JavaScript, it will use the value.

For example, without constant enum, the value set to a direction with Orientation.East will be equal to a function that looks for the value in the map to get the value. However, with a constant, the value is set in the transpiled code to 0 directly – no more function or mapping.

Drawbacks

There are not a lot of drawbacks to this. You can still use the enum with the dot notation and the name of one of the entries. You can also use the name of the enum with the square brackets and the name of one of the entries.

However, you won’t be able to use the square brackets with the value.

The only difference is that a constant enum doesn’t allow for redefining values once they’re initialized, which is allowed with default non-constant enum. However, in both cases, it’s possible to add an entry using the square brackets.