Codility - MissingInteger

MissingInteger.js

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');
// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    // write your code in JavaScript (Node.js 0.12)
    var counting = [];
    for ( var i = 0; i < A.length; i++) {
        if(counting[A[i]]){
            counting[A[i]] ++;
        } else {
            counting[A[i]] = 1;
        }    
    }
    
    for (var i=1; i < counting.length; i++) {
        if (!counting[i]) {
            return i;
        } 
    }
    return (counting.length > 0) ? counting.length : 1;
}