如何遍历对象数组并使用Javascript对特定属性求和[关闭]答案

【问题标题】：How to iterate through an array of objects and sum a specific property with Javascript [closed]如何遍历对象数组并使用Javascript对特定属性求和[关闭]
【发布时间】：2021-09-22 12:09:23
【问题描述】：

我有一组对象，我需要滚动它们并添加 Maria 和 Cristiano 的战斗胜利，最后我需要显示每个人赢得了多少 BattleWon，如示例所示

 const array = [
      {
        id: '147acaa3-363c-4a28-af43-fcc035a1d500',
        arena: 'Philippine Arena',
        firstParticipant: {
          address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
          name: 'Cristiano',
          battlesWon: 0
        },
        secondParticipant: {
          address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
          name: 'Maria',
          battlesWon: 1
        },
        logs: [ [Object] ]
      },
      {
        id: 'b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab',
        arena: 'Greensboro Coliseum',
        firstParticipant: {
          address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
          name: 'Maria',
          battlesWon: 1
        },
        secondParticipant: {
          address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
          name: 'Cristiano',
          battlesWon: 0
        },
        logs: [ [Object] ]
      }
    ]

预期：

{
  Cristiano: 0,
  Maria: 2
}

【问题讨论】：

这能回答你的问题吗？ Creating a SUM of nested object values in JavaScript

标签： javascript arrays

【解决方案1】：

我认为一种可能的解决方案是使用 forEach 循环遍历数组，然后将值添加到结果字典中，如您在此处看到的：

let list = [
    {
        id: '147acaa3-363c-4a28-af43-fcc035a1d500',
        arena: 'Philippine Arena',
        firstParticipant: {
            address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
            name: 'Cristiano',
            battlesWon: 0
        },
        secondParticipant: {
            address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
            name: 'Maria',
            battlesWon: 1
        },
        logs: [[Object]]
    },
    {
        id: 'b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab',
        arena: 'Greensboro Coliseum',
        firstParticipant: {
            address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
            name: 'Maria',
            battlesWon: 1
        },
        secondParticipant: {
            address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
            name: 'Cristiano',
            battlesWon: 0
        },
        logs: [[Object]]
    }
]

let results = {
    Cristiano: 0,
    Maria: 0
}

list.forEach(arena => {
    results[arena.firstParticipant.name] += arena.firstParticipant.battlesWon
    results[arena.secondParticipant.name] += arena.secondParticipant.battlesWon
})

console.log(results)

【讨论】：

【解决方案2】：

您可以使用Array.prototype.reduce 遍历数据中的每个条目，然后将参与者数据写入累加器。优点是您不需要在函数之外创建单独的对象。

然后，在reduce() 的每次迭代中，您只需使用一个通用函数将参与者数据写入累加器：

function handleParticipant(participant, acc) {
  const { name, battlesWon } = participant;
  acc[name] = (acc[name] || 0) + battlesWon;
}

真正的逻辑在acc[name] = (acc[name] || 0) + battlesWon这一行，基本上就是说：如果在字典中找到name，则将battlesWon添加到其值中，否则将battlesWon添加到初始值@987654328 @。

请参阅下面的概念验证：

const data = [
  {
    id: '147acaa3-363c-4a28-af43-fcc035a1d500',
    arena: 'Philippine Arena',
    firstParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
      name: 'Cristiano',
      battlesWon: 0
    },
    secondParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
      name: 'Maria',
      battlesWon: 1
    }
  },
  {
    id: 'b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab',
    arena: 'Greensboro Coliseum',
    firstParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
      name: 'Maria',
      battlesWon: 1
    },
    secondParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
      name: 'Cristiano',
      battlesWon: 0
    }
  }
];

function handleParticipant(participant, acc) {
  const { name, battlesWon } = participant;
  acc[name] = (acc[name] || 0) + battlesWon;
}

const battlesWonByName = data.reduce((acc, cur) => {
  const { firstParticipant, secondParticipant } = cur;
  
  handleParticipant(firstParticipant, acc);
  handleParticipant(secondParticipant, acc);
  
  return acc;
}, {});

console.log(battlesWonByName);

【讨论】：

【解决方案3】：

请使用此代码。

const arr = [
  {
    id: '147acaa3-363c-4a28-af43-fcc035a1d500',
    arena: 'Philippine Arena',
    firstParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
      name: 'Cristiano',
      battlesWon: 0
    },
    secondParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
      name: 'Maria',
      battlesWon: 1
    },
    logs: [ [Object] ]
  },
  {
    id: 'b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab',
    arena: 'Greensboro Coliseum',
    firstParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
      name: 'Maria',
      battlesWon: 1
    },
    secondParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
      name: 'Cristiano',
      battlesWon: 0
    },
    logs: [ [Object] ]
  }
]

let result = {};

arr.forEach(val => {
  ['firstParticipant', 'secondParticipant'].forEach(key => {
    if(result.hasOwnProperty(val[key]['name'])) {
      result[val[key]['name']] += val[key]['battlesWon'];
    } else {
      result[val[key]['name']] = val[key]['battlesWon'];
    }
  })
})

console.log(result);

【讨论】：

【解决方案4】：

你可以这样做：

const json = [
  {
    id: '147acaa3-363c-4a28-af43-fcc035a1d500',
    arena: 'Philippine Arena',
    firstParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
      name: 'Cristiano',
      battlesWon: 0
    },
    secondParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
      name: 'Maria',
      battlesWon: 1
    },
    logs: [ [Object] ]
  },
  {
    id: 'b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab',
    arena: 'Greensboro Coliseum',
    firstParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644',
      name: 'Maria',
      battlesWon: 1
    },
    secondParticipant: {
      address: '0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661',
      name: 'Cristiano',
      battlesWon: 0
    },
    logs: [ [Object] ]
  }
]

var newJson = new Array();
json.map((battle) => {
    newJson[battle.firstParticipant.name] = newJson[battle.firstParticipant.name] != null ? battle.firstParticipant.battlesWon + newJson[battle.firstParticipant.name] :  battle.firstParticipant.battlesWon;
    newJson[battle.secondParticipant.name] = newJson[battle.secondParticipant.name] != null ? battle.secondParticipant.battlesWon + newJson[battle.secondParticipant.name] :  battle.secondParticipant.battlesWon;
});

【讨论】：

使用.forEach 而不是.map。 Map 返回新数组，但 foreach 遍历数组元素

【解决方案5】：

您可以使用reduce轻松实现结果

arr.reduce((acc, curr) => {
  const { firstParticipant: { name: a, battlesWon: m }, secondParticipant: { name: b, battlesWon: n } } = curr;
  acc[a] = (acc[a] ?? 0) + m
  acc[b] = (acc[b] ?? 0) + n
  return acc;
}, {});

1)

const arr = [
  {
    id: "147acaa3-363c-4a28-af43-fcc035a1d500",
    arena: "Philippine Arena",
    firstParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661",
      name: "Cristiano",
      battlesWon: 0,
    },
    secondParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644",
      name: "Maria",
      battlesWon: 1,
    },
    logs: [[Object]],
  },
  {
    id: "b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab",
    arena: "Greensboro Coliseum",
    firstParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644",
      name: "Maria",
      battlesWon: 1,
    },
    secondParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661",
      name: "Cristiano",
      battlesWon: 0,
    },
    logs: [[Object]],
  },
];

const result = arr.reduce((acc, curr) => {
  const {
    firstParticipant: { name: name1, battlesWon: battlesWon1 },
    secondParticipant: { name: name2, battlesWon: battlesWon2 },
  } = curr;

  acc[name1] ? (acc[name1] += battlesWon1) : (acc[name1] = battlesWon1);
  acc[name2] ? (acc[name2] += battlesWon2) : (acc[name2] = battlesWon2);

  return acc;
}, {});

console.log(result);

2)

const arr = [
  {
    id: "147acaa3-363c-4a28-af43-fcc035a1d500",
    arena: "Philippine Arena",
    firstParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661",
      name: "Cristiano",
      battlesWon: 0,
    },
    secondParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644",
      name: "Maria",
      battlesWon: 1,
    },
    logs: [[Object]],
  },
  {
    id: "b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab",
    arena: "Greensboro Coliseum",
    firstParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644",
      name: "Maria",
      battlesWon: 1,
    },
    secondParticipant: {
      address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661",
      name: "Cristiano",
      battlesWon: 0,
    },
    logs: [[Object]],
  },
];

const result = arr.reduce((acc, { firstParticipant, secondParticipant }) => {
  acc[firstParticipant.name]
    ? (acc[firstParticipant.name] += firstParticipant.battlesWon)
    : (acc[firstParticipant.name] = firstParticipant.battlesWon);

  acc[secondParticipant.name]
    ? (acc[secondParticipant.name] += secondParticipant.battlesWon)
    : (acc[secondParticipant.name] = secondParticipant.battlesWon);
  return acc;
}, {});

console.log(result);

【讨论】：

【解决方案6】：

如果您使用的是 nodeJs 并且您有一个额外的 'Johnn' 来检查这将是

有用

import lodash  from 'lodash';
const arr = [
    {
      id: "147acaa3-363c-4a28-af43-fcc035a1d500",
      arena: "Philippine Arena",
      firstParticipant: {
        address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661",
        name: "Cristiano",
        battlesWon: 0,
      },
      secondParticipant: {
        address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644",
        name: "Maria",
        battlesWon: 1,
      },
      logs: [[Object]],
    },
    {
      id: "b2ef2d28-d84d-4cc9-946f-3d57b8ce05ab",
      arena: "Greensboro Coliseum",
      firstParticipant: {
        address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075644",
        name: "John",
        battlesWon: 1,
      },
      secondParticipant: {
        address: "0x3ba59bcc1a02cb46e7de35fb0bacc860bf075661",
        name: "Cristiano",
        battlesWon: 0,
      },
      logs: [[Object]],
    },
  ];

const input = ['Cristiano', 'Maria', 'John'];
const attr = [{
    selector: 'firstParticipant.name',
    sum: 'firstParticipant.battlesWon'
},{
    selector: 'secondParticipant.name',
    sum: 'secondParticipant.battlesWon'
}];

function getResult(arr, attr, input) {
    let result = {};
    arr.forEach((obj) => {
        attr.forEach((param)=>{
            let index = input.indexOf(lodash.get(obj, param.selector));
            let value = lodash.get(obj, param.sum);
            if( index > -1) {
                result[input[index]] = result[input[index]] ? (result[input[index]] + value) : value;
            }
        });
    });
    return result;
}
console.log(getResult(arr, attr, input));

【讨论】：