javascript - 如何对数组中的对象进行分组

Question

我有一个对象数组，我想根据两个键对它的对象进行分组

var arr = [ 
  {"name": "apple", "id": "apple_0","c":'20'}, 
  {"name": "dog",   "id": "dog_1","c":'10'}, 
  {"name": "apple", "id": "apple_0","c":'30'},
  {"name": "dog",   "id": "dog_1","c":'10'},
];

我期待的结果是

var final = [ 
  {"name": "apple", "id": "apple_0","c":'50'}, 
  {"name": "dog",   "id": "dog_1","c":'20'}
];

场景是这样的 - 我想根据 name 和 id 对对象进行分组。如果在最终数组中找到 name 和 id，则对其 c 求和。

我试过这个:

var final = [];
for(var i = 0; i<arr.length; i++){
    var obj = {};
    obj = arr[i];
    for(var j = 0; j<final.length; j++){
        if((obj[name] !== final[j].name) && (obj[id] !== final[j].id)){
          final.push(obj)
        }else{
            //addition of key `c` in existing object in `final` array 
        }
    }
} 

但内部 for 循环不起作用，并且由于连续循环执行而挂起我的系统。

请让我知道如何修复它或任何其他逻辑以获得最终结果。

Answer 1

这是一个使用哈希表 和#reduce() 函数的解决方案 - 请参见下面的演示:

var arr = [{"name": "apple", "id": "apple_0","c":'20'},{"name": "dog",   "id": "dog_1","c":'10'}, {"name": "apple", "id": "apple_0","c":'30'},{"name": "dog",   "id": "dog_1","c":'10'}];

var result = arr.reduce(function(hash){
  return function(p,c){
    if(hash[c.id])
      hash[c.id].c = +hash[c.id].c + +c.c
    else {
      hash[c.id] = hash[c.id] || c;
      p.push(hash[c.id]);
    }
    return p;
  }
}(Object.create(null)), []);

console.log(result);

.as-console-wrapper{top:0;max-height:100%!important;}