SelectionSort Algorithm

The Selection Sort algorithm is the simplest sorting algorithm in which the current and the smallest element are repeatedly exchanged if they are in the wrong order.

Functionality

First run

the for-loop outputs the smallest number of the array: 1
after this the current number array[i] (5) and the smallest number (1) get swapped

from...
[5,3,8,1,4,9]
to ...
[1,3,8,5,4,9]

Second run

the for-loop outputs the smallest number of the array starting at array[1] (position 2): 3
the current number array[i] (3) and the smallest number (3) get swapped and nothing changes in this run

from...
[1,3,8,5,4,9]
to ...
[1,3,8,5,4,9]

Third run

the for-loop outputs the smallest number of the array starting at array[2] (position 3): 4
the current number array[i] (8) and the smallest number (4) get swapped

from...
[1,3,8,5,4,9]
to ...
[1,3,4,5,8,9]

Fourth run

the for-loop outputs the smallest number of the array starting at array[3] (position 4): 5
the current number array[i] (5) and the smallest number (5) get swapped and nothing changes in this run

from...
[1,3,8,5,4,9]
to ...
[1,3,4,5,8,9]

... the algorithm goes through the whole array until the last number

Last run

the for-loop outputs the smallest number of the array starting at array[5] (position 6): 9
the current number array[i] (9) and the smallest number (9) get swapped

from...
[1,3,8,5,4,9]
to ...
[1,3,4,5,8,9]

Code

at first the algorithm goes through the whole array and chooses the smallest number
with every run i increases by 1 => this means i always is the current number/run

var min = i;

for (var j = i; j < arr.length; j++){
	if (arr[j] <= arr[min]){
		min = j; // if the current number is greater than arr[j], then min will be changed to i
	}
}

after we got the position of the smallest number through the for-loop, we change the current and the smallest number

var smallestNumber = arr[min];
arr[min] = arr[i];
arr[i] = smallestNumber;

after that step we increase i for checking the next number in the array
with i we call the recursive function selectionsort(i)

selectionsort(arr, i);