TypeScript - How to declare static methods on enum

If you are coming from the Java world you might be interested in being able to declare static methods on the enum itself.

Here is a way to do it, by using TypeScript namespace.

enum MyEnum {
    ALFA = 'ALFA',
    BRAVO = 'BRAVO',
    CHARLIE = 'CHARLIE',
    UNKNOWN = 'UNKNOWN'
}

namespace MyEnum {

    export const ALL_VALUES: string[] = Object.values(MyEnum);

    export function parse(val: string): MyEnum {
        if(!val) {
            return MyEnum.UNKNOWN;
        }

        const found = ALL_VALUES.indexOf(val);

        return ALL_VALUES[found] || MyEnum.UNKNOWN;
    }
}

function checkEnumValue(val: string): void {
    const enumValue = MyEnum.parse(val);
    console.log(`MyEnum.parse('${val}') ==> '${enumValue}'`);
}

checkEnumValue(null);
checkEnumValue("");
checkEnumValue("ALFA");
checkEnumValue("Quebec");

Tested with TypeScript v3.6.3