randomize all elements in a array inplace

randomize all elements in an array (in-place algorithms) take no space and its fastest among all random algorithms.

//fastest algo to randomize array values without any space inplace  

Array.prototype.swap=function(startIndex,endIndex=this.length-1)

{

   let temp=this[startIndex];

   this[startIndex]=this[endIndex];

   this[endIndex]=temp;

   return this;

};

Array.prototype.random=function()

{

    const randomFunction=(min,max)=>{

        return Math.round(Math.random()*(max-min))+min;

    }

    for(let i=0;i<this.length;i++)

    {

       this.swap(i,randomFunction(i,this.length-1));

    }

    return this;

}

var newArr=[10,9,8,7,21,12,13];

console.log(newArr.random())