Iterate Through All an Array's Items Using Nested For Loops

JavaScript
1

Tell us what’s happening:
I’ve figured out the solution to this problem using one for loop.

But my initial inclination was to use a nested for loop since I was dealing with nested arrays. I don’t understand why I get 3 outputs of the passing array in the console.

Your code so far


function filteredArray(arr, elem) {
  let newArr = [];
    for (let i = 0; i < arr.length; i++){
      for (let k = 0; k < arr[i].length; k++){
        if (arr[i].indexOf(elem) == -1){
          newArr.push(arr[i])
        }
      }
    } 
  return newArr;
}

// change code here to test different cases:
console.log(filteredArray([[3, 2, 3], [1, 6, 3], [3, 13, 26], [19, 3, 9]], 3));

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-data-structures/iterate-through-all-an-arrays-items-using-for-loops/

2

just to be clear , can you clarify what you meant by “I get 3 outputs” by cutting and pasting the console results into your original question? thanks.

3

In your case, the nested loop operation repeats the search arr[i].length - 1 times. So, if one array passed the filter, it will be added as many times as the inner loop runs.

Just look at what the inner loop is doing.

4

in the outer loop you are considering the length of arr(which is 4 in this case) and in the inner loop you are looping through and are taking the length/the no of elements inside all 4 arrays(that is 3 in all 4 arrays ). when the i value is 0, inner loop runs until the value of 2 (i.e 3 times(0,1,2) as the condition is k<3) before it terminates when k becomes 3 and then the i value is incremented by 1 and the same process is repeated.