var myArray = [];

for(var i=0; i<100; i++){

  myArray.push(i+1);

}

console.log(myArray);

​

function chunk(arr, size){

  var chunkedArr = [];

  var noOfChunks = Math.ceil(arr.length/size);

  console.log(noOfChunks);

  for(var i=0; i<noOfChunks; i++){

    chunkedArr.push(arr.slice(i*size, (i+1)*size));

  }

   return chunkedArr;

}

​

var chunkedArr = chunk(myArray, 3);

console.log(chunkedArr);