find smallest integer

smallInt.js

function smallInt(A) {
    let s = 1;
    A.sort((a, b) => a - b)
    if (A[0] >= 0) {
        if (A.indexOf(1) === -1) {
          return 1;
        }
    }
    for (i=0; i<A.length; i++){
        s = A[i]+1;
        s = s <= 0 ? 1 : s
        if (A.indexOf(s) === -1) break;
    }
    return s;
}

//Version below ins in O(N)
function solution(A) {
    A.sort((a, b) => a - b)
    if (A[A.length-1] < 1)  return 1;
    if (A[A.length-1] === 1) return 2;
    if (A[0] > 1)  return 1;
    var x = A.indexOf(1);
    if (x === -1) return 1;
    A = A.slice(x);
    for (i=0; i<A.length-1;i++){
    	if (A[i+1] - A[i] > 1){ 
    		var s = A[i] + 1;
    	    if (s < 1) return 1;
    	    else return s;
    	}
    }
    return A[A.length-1]+1;
}