js数组怎么按属性分类，不用嵌套遍历

把后端返回的数据遍历一遍
遍历成如下形式

[  
  {  
    gysid:a,  
    goodsList: [{spid:01,gysid:a，spname:商品1，price：2}，{spid:02,gysid:a，spname:商品2，price：2}]  
  },  
  {  
    gysid:b,  
    goodsList: [{spid:01,gysid:b，spname:商品3，price：2}]  
  }  
]

进行页面渲染即可

let arr = [{spid:'01',gysid:"a",spname:"商品1",price:2},  
{spid:'02',gysid:"a",spname:"商品2",price:21},  
{spid:'03',gysid:"b",spname:"商品3",price:56},  
{spid:'04',gysid:"c",spname:"商品4",price:21},  
{spid:'05',gysid:"c",spname:"商品5",price:23}]  

let obj = arr.reduce((last,item)=>{  
     if(last[item.gysid]){  
         last[item.gysid].push(item)  
     }else{  
         last[item.gysid]=[item]  
     }  
    return last  
},{})  

console.log(obj);  

循环obj即可