different sorting algorithms implemented in JS

sorting.js

const test = [5,6,1,7,7,7,7,3,5,2,2,9,9,0,9];

const insertionSort = (arr)=>{
  for(let i = 1; i < arr.length; i++){
    let current = arr[i];
    let j = i-1;
    while(j >=0 && arr[j] > current) {
      arr[j+1] = arr[j]
      j--;
    }
    arr[j+1] = current;
  }
return arr;
};



const quickSort = (arr) =>{
  if(arr.length < 1) return arr;
  const [pivot,...rest] = arr;
  const left = [], right = [];
  for (let i = 0; i < rest.length; i++) {
    if(rest[i] < pivot) left.push(rest[i]);
    else right.push(rest[i]);
  }
  
  return quickSort(left).concat(pivot).concat(quickSort(right));
};

const mergeSort = (arr) => {
  if(arr.length<=1) return arr;
  const middle = Math.floor(arr.length/2);
  const left = mergeSort(arr.slice(0,middle));
  const right = mergeSort(arr.slice(middle));
  const result = [];
  while(right.length && left.length) {
    if(left[0] < right[0]){
      result.push(left.shift());
    } else {
      result.push(right.shift());
    }
  }
  return result.concat(left).concat(right);
};
console.log(insertionSort(test.slice()))
console.log(quickSort(test.slice()));
console.log(mergeSort(test.slice()));