循环遍历一个对象，只返回某些键及其值

如何解决循环遍历一个对象，只返回某些键及其值

给定以下对象，我如何遍历此对象以获取键和值，但仅获取以下键：

    "myName": "Demo"
    "active": "Y"
    "myCode": "123456789"
    "myType": 1


let a = {
    "values": {
        "myName": "Demo","active": "Y","myCode": "123456789","myType": 1,"myGroups": [
            {
                "myGroupName": "Group 1","myTypes": [
                    {
                        "myTypeName": "323232","myTypeId": "1"
                    }
                ]
            },{
                "myGroupName": "Group 2","myTypes": [
                    {
                        "myTypeName": "523232","myTypeId": "2"
                    }
                ]
            }
        ]
    }
}

我试过了：

for (const [key,value] of Object.entries(a.values)) {
  console.log(`${key}: ${value}`);
For}

但这将返回所有键及其值。

解决方法

您可以使用字典（数组）来包含要为其提取属性的键，然后使用 reduce 对值进行 Object.entries 以生成仅与这些条目匹配的新对象 {{ 3}} 在字典中。

let a = {
  "values": {
    "myName": "Demo","active": "Y","myCode": "123456789","myType": 1,"myGroups": [{
        "myGroupName": "Group 1","myTypes": [{
          "myTypeName": "323232","myTypeId": "1"
        }]
      },{
        "myGroupName": "Group 2","myTypes": [{
          "myTypeName": "523232","myTypeId": "2"
        }]
      }
    ]
  }
}

const arr = [ 'myName','active','myCode','myType' ];

const out = Object.entries(a.values).reduce((acc,[key,value]) => {
  if (arr.includes(key)) acc[key] = value;
  return acc;
},{});

console.log(out);

,

最好的答案是设置所需键的数组，然后迭代那个数组而不是原始对象条目的数组。这就是您实现这一目标的方式：

let a = {
  values: {
    myName: "Demo",active: "Y",myCode: "123456789",myType: 1,myGroups: [{
      myGroupName: "Group 1",myTypes: [{
        myTypeName: "323232",myTypeId: "1"
      }]
    },{
      myGroupName: "Group 2",myTypes: [{
        myTypeName: "523232",myTypeId: "2"
      }]
    }]
  }
};

const keys = ['myName','myType'];

const cherryPick = (obj,keys) => keys.reduce((a,c) => (a[c] = obj[c],a),{});

console.log(cherryPick(a.values,keys));

以上示例适用于许多提供的密钥。如果提供的对象中不存在键，则其值将是未定义的。如果您只想保留有值的属性，只需向 cherryPick() 函数添加一个可选过滤器，如下所示：

let test = {
  a: 1,b: 2
};

const keys = ['a','b','c'];

const cherryPick = (obj,keys,filter = 0) => keys.filter(key => filter ? obj[key] : 1).reduce((acc,key) => (acc[key] = obj[key],acc),{});

console.log('STORE undefined :: cherryPick(test,keys)',cherryPick(test,keys));
console.log('FILTER undefined :: cherryPick(test,1)',true));

/* Ignore this */ .as-console-wrapper { min-height: 100%; }