FirstRecurringCharacter

function firstRecurringCharacter(arr) {
    
    const map = new Map();
    
    for( i = 0; i < arr.length; i++) {
        console.log(map[arr[i]]);
        if(!map[arr[i]]) {
            map[arr[i]] = true;
        }
        else {
            return map[arr[i]];
        }
    }
    return undefined;
}

console.log(firstRecurringCharacter([2,3,5,7,8,2]));