如何取键值的总和？

Question

我有一个 collection 这样的：

{
    "2.2": { 
        "BALL":{"white":9,"black":11,"red":4},
        "BAG":{"white":2,"black":11,"red":1},
        "COVER":{"white":3,"black":8,"red":1}
    },
    "2.3": {
        "BALL":{"white":1,"black":0,"red":7},
        "BAG":{"white":3,"black":0,"red":0},
        "COVER":{"white":9,"black":2,"red":28}
    }
}

我想计算关于“2.2”和“2.3”的颜色总和（白色、黑色、红色）。

输出所需的输出应该是这样的：

{
    "2.2": {"white": 14, "black": 30, "red": 6},
    "2.3": {"white": 13, "black": 2, "red": 35}
}

我试过使用 underscore .map 函数，但我无法正确理解它。任何人都可以帮忙。？ PS: 需要仅使用 underscore.js 的解决方案。

Answer 1

尝试：

var obj = {
    "2.2": {
        "BALL": {
            "white": 9, "black": 11, "red": 4
        },
        "BAG": {
            "white": 2, "black": 11, "red": 1
        },
        "COVER": {
            "white": 3, "black": 8, "red": 1
        }
    },
    "2.3": {
        "BALL": {
            "white": 1, "black": 0, "red": 7
        },
        "BAG": {
            "white": 3, "black": 0, "red": 0
        },
        "COVER": {
            "white": 9, "black": 2, "red": 28
        }
    }
}
var w = 0;
for(var i in obj){
    for(var j in obj[i]){
        w +=obj[i][j]['white'];
    }
}

更新：

var obj = {
    "2.2": {
        "BALL": {
            "white": 9, "black": 11, "red": 4
        },
        "BAG": {
            "white": 2, "black": 11, "red": 1
        },
        "COVER": {
            "white": 3, "black": 8, "red": 1
        }
    },
    "2.3": {
        "BALL": {
            "white": 1, "black": 0, "red": 7
        },
        "BAG": {
            "white": 3, "black": 0, "red": 0
        },
        "COVER": {
            "white": 9, "black": 2, "red": 28
        }
    }
}
for (var i in obj) {
    var tmp = {
        white: 0,
        black: 0,
        red: 0
    };
    for (var j in obj[i]) {
        tmp['white'] += obj[i][j]['white'];
        tmp['black'] += obj[i][j]['black'];
        tmp['red'] += obj[i][j]['red'];
    }
    obj[i] = tmp
}
console.log(obj);

Answer 2

这是underscore.js解决方案。

_.mapObject(collections, function(collection) {
  return _.reduce(collection, function(memo, col) {
    // credit: Bergi on 
    // the following line reads:
    // for (var p in col) => loop all properties in col
    // memo[p] = ... => assign memo[p] as ...
    // (p in memo ? memo[p] : 0) => IF property p exists in memo, then memo[p], otherwise 0
    // + col[p] => add col's p
    for (var p in col) { memo[p] = (p in memo ? memo[p] : 0) + col[p]; }
    return memo;
  }, {});
});

如何取键值的总和？

How to take the sum of the value of keys?

javascript

collections

jquery

underscore.js