Cannot assign a string value to typescript enum (Initializer type string not assignable to variable type)

Question

It seems that from TypeScript 2.4 onwards String Enums are a feature.

However the following does not work:

enum Foo {
    A = "A",
    B = "B"
}

var foo : Foo = "A";

Initializer type string not assignable to variable type Foo

String literals work:

type Foo = "A" | "B";

But what if I want to use an enum? Is there a way around this?

Answer 1

You can use an index expression to get the value of the enum:

enum Foo {
    A = "A",
    B = "BB"
}

var foo : Foo = Foo["A"];
var fooB : Foo = Foo["B"];

Note that the key will be the name of the member not the value.

You could also use a type assertion, but you will not get errors if you assign a wrong value:

var foo : Foo = "A"  as Foo;
var foo : Foo = "D"  as Foo; // No error