How to iterate over a nested object array in Javascript

Question

How can I iterate through a nested array of objects in Javascipt? I have an object named obj. I want to retrieve the object where in is credit and out is bank.

// 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);

This is the data:

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
  }]
}]

Expected Output:

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

as per you current expected output, you cant same same key in object — Harish
– Harish, Commented Apr 3, 2019 at 8:36
The output is invalid, since you can't have the same key in the same object. Perhaps you wanted an array of objects instead? Besides, you are considering t as the inner array, though t is an object containing a dynamic key (ctob, btob) and, for that key, an array of objects. You likely want to filter on that array instead. — briosheje
– briosheje, Commented Apr 3, 2019 at 8:37

trincot · Accepted Answer · 2019-04-03 08:54:32Z

Here is a functional style solution:

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);

But like was commented, if your object key "ctob" means "credit to bank", then there should be no need to test for nested "credit" and "bank" property values.

Terry · Accepted Answer · 2019-04-03 08:51:07Z

Since the object referenced by the key ctob matches your selection requirement, you can simply do this:

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);

Of course, if you want to be absolutely sure, you will have to go through each nested object. Remember that since each nested array has a length of one (it is a single-length array of objects), you need to use [0] to access the correct object before comparing its keys:

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);

S.Orioli · Accepted Answer · 2019-04-03 09:00:35Z

You have to iterate trought the array and on each property of single array item; I write the code in a more readable way, adding some comments:

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);

Vikash_Singh · Accepted Answer · 2019-04-03 08:57:22Z

0

Here is your solution:

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);

answered Apr 3, 2019 at 8:57

Vikash_Singh

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