javascript - 在 javascript 或 jquery 中迭代多级对象

Question

我从 ajax 调用返回了这个 json:

{"datasets":[
    {"data":[0,0,2,0,1,0,0,0,0,0,5,2], "service_ID": 1},
    {"data":[0,0,0,0,0,0,0,0,0,0,1,3], "service_ID": 2},
    {"data":[0,0,0,0,0,0,0,0,0,0,0,2], "service_ID": 3},
    {"data":[0,0,0,0,0,0,0,0,0,0,0,4], "service_ID": 4},
    {"data":[0,0,0,0,0,0,0,0,0,0,0,1], "service_ID": 5}
   ]
}

data 对象中的每个元素都是一个月的值，从 1 月到 12 月(一个包含 12 个元素的数组)

我需要在datasets内部循环以获取data对象内的每个值并获得总和，在本例中:2+1+5+2+ 1+3+2+4+1 = 21

我已经尝试过

var total = 0;

          $.each(datasets, function(index, data) {
                $.each(data, function(index, month) {
                    $.each(month, function(index, value) {
                        total = total + value;
                    });
                });
          });

但我收到 TypeError: invalid 'in' operand a 错误。

获得我需要的东西的最佳方式是什么？

Answer 1

使用减少

obj.datasets.reduce( function( a, b ){  //
   return a + b.data.reduce( (c, d) => c + d , 0); // 0 is the accumulator for data property of each item in the array 
} , 0); //0 is the accumulator which is the final output

甚至更短

obj.datasets.reduce( ( a, b ) => a + b.data.reduce( ( c, d ) => c + d , 0)  , 0 );

演示

var obj = {"datasets":[
    {"data":[0,0,2,0,1,0,0,0,0,0,5,2], "service_ID": 1},
    {"data":[0,0,0,0,0,0,0,0,0,0,1,3], "service_ID": 2},
    {"data":[0,0,0,0,0,0,0,0,0,0,0,2], "service_ID": 3},
    {"data":[0,0,0,0,0,0,0,0,0,0,0,4], "service_ID": 4},
    {"data":[0,0,0,0,0,0,0,0,0,0,0,1], "service_ID": 5}
   ]
};

var output = obj.datasets.reduce( function( a, b ){ 
   return a + b.data.reduce( (c, d) => c + d , 0);
} , 0);

console.log( output );