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
 }]

• Harish: as per you current expected output, you cant same same key in object
• briosheje: 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.
• José Manuel Blasco: Also your object has missing "," at the end of some lines.
• Senthil: @briosheje yes, updated the output
• Senthil: @manuman94 apologies and updated changes

Answer 1

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.

Answer 2

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);

Answer 3

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);

Answer 4

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);