如何在Javascript中迭代嵌套对象数组

Question

如何在Javascipt中迭代嵌套的对象数组？我有一个名为obj的对象。我想要检索in是credit和out是bank的对象。

// I have tried using filter but returns empty array
const s = obj.filter(function(t){
  return t.in == "credit" && t.out == "bank";
})
console.log(s);

这是数据：

var obj = [{
  "btob": [{
    "id": "trans",
    "in": "bank",
    "out": "bank",
    "value": 10
  }],
  "ctob": [{
    "id": "trans",
    "in": "credit",
    "out": "bank",
    "value": 20
  }],
  "dtob": [{
    "id": "trans",
    "in": "debit",
    "out": "bank",
    "value": 30
  }]
}, {
  "btob": [{
    "id": "fund",
    "in": "bank",
    "out": "bank",
    "value": 10
  }],
  "ctob": [{
    "id": "fund",
    "in": "credit",
    "out": "bank",
    "value": 10
  }],
  "dtob": [{
    "id": "fund",
    "in": "debit",
    "out": "bank",
    "value": 30
  }]
}]

预期产出：

  [{
    "id": "trans",
    "in": "credit",
    "out": "bank",
    "value": 20
  },
  {
    "id": "fund",
    "in": "credit",
    "out": "bank",
    "value": 10
  }]

Answer 1

这是一个功能风格的解决方案：

data.flatMap(obj => Object.values(obj).flatMap(arr => 
    arr.filter(t => t.in === "credit" && t.out === "bank")
));

const data = [{"btob": [{"id": "trans","in": "bank","out": "bank","value": 10}],"ctob": [{"id": "trans","in": "credit","out": "bank","value": 20}],"dtob": [{"id": "trans","in": "debit","out": "bank","value": 30}]}, {"btob": [{"id": "fund","in": "bank","out": "bank","value": 10}],"ctob": [{"id": "fund","in": "credit","out": "bank","value": 10}],"dtob": [{"id": "fund","in": "debit","out": "bank","value": 30}]}];

const result = data.flatMap(obj => Object.values(obj).flatMap(arr => arr.filter(t => t.in === "credit" && t.out === "bank")));

console.log(result);

但就像被评论一样，如果你的对象密钥“ctob”意味着“贷记到银行”，那么就不需要测试嵌套的“信用”和“银行”属性值。

Answer 2

由于密钥ctob引用的对象符合您的选择要求，您可以简单地执行此操作：

const output = obj.map(entry => {
  return entry.ctob[0];
});

var obj = [{
  "btob": [{
    "id": "trans",
    "in": "bank",
    "out": "bank",
    "value": 10
  }],
  "ctob": [{
    "id": "trans",
    "in": "credit",
    "out": "bank",
    "value": 20
  }],
  "dtob": [{
    "id": "trans",
    "in": "debit",
    "out": "bank",
    "value": 30
  }]
}, {
  "btob": [{
    "id": "fund",
    "in": "bank",
    "out": "bank",
    "value": 10
  }],
  "ctob": [{
    "id": "fund",
    "in": "credit",
    "out": "bank",
    "value": 10
  }],
  "dtob": [{
    "id": "fund",
    "in": "debit",
    "out": "bank",
    "value": 30
  }]
}];

const output = obj.map(entry => {
  return entry.ctob[0];
});

console.log(output);

当然，如果您想要绝对确定，则必须遍历每个嵌套对象。请记住，由于每个嵌套数组的长度为1（它是一个单长度的对象数组），因此在比较其键之前，需要使用[0]来访问正确的对象：

const output = [];
obj.forEach(entry => {
  Object.keys(entry).forEach(key => {
    const entity = entry[key][0];
    if (entity.in === 'credit' && entity.out === 'bank') {
      output.push(entity);
    }
  });
});

var obj = [{
  "btob": [{
    "id": "trans",
    "in": "bank",
    "out": "bank",
    "value": 10
  }],
  "ctob": [{
    "id": "trans",
    "in": "credit",
    "out": "bank",
    "value": 20
  }],
  "dtob": [{
    "id": "trans",
    "in": "debit",
    "out": "bank",
    "value": 30
  }]
}, {
  "btob": [{
    "id": "fund",
    "in": "bank",
    "out": "bank",
    "value": 10
  }],
  "ctob": [{
    "id": "fund",
    "in": "credit",
    "out": "bank",
    "value": 10
  }],
  "dtob": [{
    "id": "fund",
    "in": "debit",
    "out": "bank",
    "value": 30
  }]
}];

const output = [];
obj.forEach(entry => {
  Object.keys(entry).forEach(key => {
    const entity = entry[key][0];
    if (entity.in === 'credit' && entity.out === 'bank') {
      output.push(entity);
    }
  });
});

console.log(output);

Answer 3

你必须遍历数组和单个数组项的每个属性;我以更易读的方式编写代码，添加一些注释：

var searched = [];

// iterate on each array elements
for(var i = 0; i < obj.length; i++){

    // take the array element as an object
    var element = obj[i];

    // iterate to all the properties of that object
    for (var property in element) {
      if (element.hasOwnProperty(property)) {
          // take the property as an object
          var propObj = element[property][0];

          // verify if the property has searched value, if so, add to the result array
          if(propObj.in == "credit" && propObj.out == "bank")
              searched.push(propObj)
      }
    }
}

// print searched array
console.log(searched);

Answer 4

这是你的解决方案：

x=[];
obj.forEach((t)=>{
   for(key in t){
     if ((t[key][0].in == "credit") && (t[key][0].out == "bank")){
       x.push(t[key][0])
     }
  }
});
console.log(x);