let chunk = function(arr, num){
num = num*1 || 1;
let ret = [];
arr.forEach(function(item, i){
if(i % num === 0){
ret.push([]);
}
ret[ret.length - 1].push(item);
});
return ret;
};
let chunk = function(arr, num){
num = num*1 || 1;
let ret = [];
arr.forEach(function(item, i){
if(i % num === 0){
ret.push([]);
}
ret[ret.length - 1].push(item);
});
return ret;
};