SelectionSort.js

function selectionSort(arr){
  for (var i = 0; i < arr.length; i++) {
    let min = i;
    // if the array index is less than the min, the min is equal to j.
    // this finds the smallest number in the iteration.
    for(let j = i + 1; j < arr.length; j++){
      if(arr[j] < arr[min]){
        min = j;
      }
    }
    // if the smallest element is not the first element, swap the element with whatever element is first.
    if(min != i){
      let tmp = arr[i];
      arr[i] = arr[min];
      arr[min] = tmp;
    }
  }
  return arr;
}

let arr = [5, 3, 1, 6, 2, 4, 7];
selectionSort(arr);
console.log(arr);