firstNotRepeatingCharacter typescript

firstNotRepeatingCharacter.ts

interface Imap{
    [key:string]:number
}

function firstNotRepeatingCharacter(s: string="abacabad"): string {


 let map:Imap ={}
    for (let e of s){
        if(e in map){
            map[e]=map[e]+1

         }
        else
            map[e]=1
            }
           for (let e in map)
        if (map[e] == 1)
            return e
    return '_'


}