方法一：

function chunk(arr, size) {
// Break it up.
var len=parseInt(arr.length/size);  
  //取模
  var remain=arr.length%size;  
  //定义各变量
  var a=[],count=1,sot=remain>0?len+1:len;   
  //装到新数组
  for ( var f = 1; f <=sot; f++) {  
    var start=size*(f-1);  
    var end=(f>len)?((f-1)*size+remain):f*size;  
    var mylocates=arr.slice(start,end);  
    a.push(mylocates);  
  }  
 return a; 
}
chunk(["a", "b", "c", "d"], 2);

方法二：

function chunk(arr, size) {
  // Break it up.
  var len = arr.length,
      m = len%size,
      div = 1,
      rArr = [];
  if(len > size){
    div = Math.floor(len/size);
    for(var i=0;i<div;i++){
      rArr.push(arr.slice(i*size,(i+1)*size));
    }
    if(m>0){
      rArr.push(arr.slice(m*(-1)));
    }
  }
  return rArr;
}