Insertion sort implemented with Javascript.

insertionSort.js

var insertionSort = function(array) {
  for(var i=1, length=array.length; i<length; i+=1) {
    var insertion = array[i], j=i;
    if (insertion < array[i-1]) {
      do {
        array[j] = array[j-1];
        j-=1;
      } while (array[j] > insertion && j > 0)
      array[j] = insertion;
    }
  }
  return array;
};

console.log(insertionSort([8,4,3,7,6,5,2,1]));