Javascript Enum To Corresponding String Value

Question

So I have this in the javascript for my page:

var TEST_ERROR  = {
        \'SUCCESS\'   :   0,
        \'FAIL\'      :   -1,
        \'ID_ERROR\'  :   -2
            


        

Answer 1

For TypeScript, there is a simpler solution (Please ignore my answer if you stick with JS):

export enum Direction {
    none,
    left = 1,
    right = 2,
    top = 4,
    bottom = 8
}

export namespace Direction {
    export function toString(dir: Direction): string {
        return Direction[dir];
    }

    export function fromString(dir: string): Direction {
        return (Direction as any)[dir];
    }
}

console.log("Direction.toString(Direction.top) = " + Direction.toString(Direction.top));
// Direction.toString(Direction.top) = top
console.log('Direction.fromString("top") = ' + Direction.fromString("top"));
// Direction.fromString("top") = 4
console.log('Direction.fromString("xxx") = ' + Direction.fromString("unknown"));
// Direction.fromString("xxx") = undefined

Because the enumeration type is compiled into an object(dictionary). You don't need a loop to find the corresponding value.

enum Direction {
    left,
    right
}

is compiled into:

{
    left: 0
    right: 1
    0: "left",
    1: "right"
}