number-enum-vs-string-enum.ts

enum Bool {True="t", False="f"}

function f(b:Bool) {
    switch(b) {
        case Bool.True: return 'true'
        case Bool.False: return 'false'
        // ERROR AS EXPECTED ✅
        case "11": return 'oops'
        // ERROR AS EXPECTED ✅
        case 11: return 'oops'
    }
}
// ERROR AS EXPECTED ✅
f("asda")
// ERROR AS EXPECTED ✅
f(11)


enum Bool2 {True, False}
// Same result with
// enum Bool2 {True=1, False=2}

function f2(b:Bool2) {
    switch(b) {
        case Bool2.True: return 'true'
        case Bool2.False: return 'false'
        // ERROR AS EXPECTED ✅
        case "11": return 'oops'
        // NO ERROR UNEXPECTED ❗️
        case 11: return 'oops'
    }
}
// ERROR AS EXPECTED ✅
f2("asda")
// NO ERROR UNEXPECTED ❗️
f2(11)