Eymen

你需要为循环/映射做些什么
这样地:

阵列:

var arr = [
    {"id":23,"site_id":13, "name":"Test 1","date":"2019-01-26T11:02:18.5661283","category":"some cats"},
    {"id":151,"site_id":15, "name":"Test 2","date":"2018-11-04T10:50:53.1756567","category":"some cats"}  
];

for循环:

for (let e of arr){
  if(e.site_id == 15){
    //do something
  }
}

你也可以为它做一个开关盒

for (let e of arr){
  switch(e.site_id){
    case 15 {
      //do something if the id is 15 
    }
    case 13{
      //do something if the id is 13 
    }
    case 99 {
      //do something if the id is 99
    }
  }
}