Missing Integer

missing_integer.js

/**
 * MISSING INTEGER
 * ---
 * Write a function:
 *    function solution(A);
 * that, given an array A of N integers, returns the smallest positive integer (greater than 0) that does not occur in A.
 * For example, given A = [1, 3, 6, 4, 1, 2], the function should return 5.
 *   Given A = [1, 2, 3], the function should return 4.
 *   Given A = [−1, −3], the function should return 1.
 *
 * Write an efficient algorithm for the following assumptions:
 *   N is an integer within the range [1..100,000];
 *   each element of array A is an integer within the range [−1,000,000..1,000,000].
 */

function solution(A) {
  const sortedArr = A.sort((a,b) => a - b);
  missingInt = 1;

  for (i=0; i<sortedArr.length; i++){
    if(sortedArr[i] == missingInt ){
      missingInt++;
    }

    if(sortedArr[i] > missingInt){
      break;
    }
  }

  return missingInt;
}