Did you try to google?
Here is what you need:
var createGroupedArray = function(arr, chunkSize) {
var groups = [], i;
for (i = 0; i < arr.length; i += chunkSize) {
groups.push(arr.slice(i, i + chunkSize));
}
return groups;
}
Usage example:
var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14];
var groupedArr = createGroupedArray(arr, 4);
var result = JSON.stringify(groupedArr);
// result: "[[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14]]"
Taken from:
http://www.frontcoded.com/splitting-javascript-array-into-chunks.html
UPDATED:
var makechunks = function(arr, chunksAmount) {
var chunkSize = Math.ceil(arr.length/chunksAmount);
var groups = [], i;
for (i = 0; i < arr.length; i += chunkSize) {
groups.push(arr.slice(i, i + chunkSize));
}
return groups;
}