Selection Sort

JavaScript Algorithm Walkthrough

Selection sort sorts an array by locating the element with the smallest value and placing it at the beginning of the array.

let theFirst = [3, 4, 56, 43, 8, 99]
function select(arr){
  let swap = (array, i1, i2) => ([arr[i1], arr[i2]]= [arr[i2], arr[i1]])
  let min
  for(let i = 0; i < arr.length; i++){
    min = i
    for(let j = i + 1; j < arr.length; j++){
      if(arr[j] < arr[min]){
        min = j
      }
    }
    if(i !== min){
      swap(arr, i, min)
    }
    return arr
}

1. Set up swap function to switch positions within the array.

let swap = (array, i1, i2) => ([arr[i1], arr[i2]]= [arr[i2], arr[i1]])

2. Create a variable for min (minimum value in array) before looping through the given array. When looping through the array, set min to i.

for(let i = 0; i < arr.length; i++){
    min = i    
}

3. Create nested loop that begins at the index after i. Create a conditional statement to check whether the value of array[j] is less than min. If so, reassign j as the new min.

for(let j = i + 1; j < arr.length; j++){
      if(arr[j] < arr[min]){
        min = j
      }
    }

4. Outside of the inner loop, check whether i was the original min. If min is no longer equal to i, switch positions within the array.

if(i !== min){
      swap(arr, i, min)
    }

5. Return sorted array outside of outer loop.