Algorithm javascript

Missing number in an array using javascript

My approach to this solution was to realize that the numbers are in consecutive order. Since the array is sorted, we can solve this in one pass by looking ahead using arr[i] + 1 and comparing that to arr[i + 1]. If arr[i + 1] is not equal to arr[i] + 1, it means that arr[i] + 1 is the missing number.

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let arr = [1,2,3,4,5,6,7,8,10];const findMissingNum = (arr) => {
  for(var i = 0; i < arr.length - 1; i++) {
    if(arr[i] + 1 != arr[i+1] ) {
      return arr[i] + 1;
    }
  }
  
  return false;
}console.log(findMissingNum(arr));