数组的拆分与重构

// 拆分数组
chunk(arr,size){
  let arr1=[];
  for(let i=0;i<arr.length;i=i+size){
    let arr2=arr;
    arr1.push(arr2.slice(i,i+size));
    console.log(i,arr2.slice(i,i+size));
  }
  return arr1;
},
// 重构数组
insert(arr1,arr2){
  let arr=[];
  let arr0=[];
  for(let i=0;i<arr1.length;i++){
    let a1=arr1.slice(i,i+1);
    let a2=[];
    let a3;
    if(arr2.slice(i,i+1)){
      if (i==arr1.length-1) {
        if(arr1.length<arr2.length){
          a3=arr2.slice(i);
          console.log("a3");
          a3.forEach((item,index,array)=>{
            item.forEach((item2,index2,array2)=>{
              a2.push(item2);
            });
          });
           // a2=arr2.slice(i);
        }
      }else{
        a2=arr2.slice(i,i+1);
      }

    }else{
       a2=[];
    }
    arr.push([...a1,a2]);
    // arr0.push(arr);
  }
  return arr;
},