Nested object iterate and return empty value key name nodejs

Question

I have an object like below

     var json = {
      "info": {
      "name": {},
      "addr": {
        "strreet": "NYC",
        "zip": 123456789
       }
     }
   }

I want to return the key where it has empty object, it may be nested for example in above json "name" is empty so I want to write a function and want to return "name" here

I have written a function for that given below

function iterate(obj) {
for (var property in obj) {
    if (obj.hasOwnProperty(property)) {
        if (typeof obj[property] == "object") {
            if (JSON.stringify(obj[property]) === '{}') {
                return property
            } else
                iterate(obj[property]);
        } else {}
    }
}
}

Now I'm calling this function like

var key = iterate(json)
console.log('Key',key)

Now key is printing undefined , any help appreciated.

void · Accepted Answer · 2018-08-13 10:09:15Z

1

You can keep a blank array and keep on pushing the empty properties in it. In the last you will need to return this array for the recursion to work and where you are calling the function recursively you will need to push its content in the empty property array.

var json = {
  "personInfo": {
    "personAttributesInfo": {
      "location": {
        "city": "New york",
        "state": {},
      }
    }
  },
  "dataInfo": {
    "travelPricing": {},
    "cost": {
      "usd": 12345,
      "someother": {},
    }
  }
};

function iterate(obj) {
  var emptyProperties = [];
  for (var property in obj) {
    if (obj.hasOwnProperty(property)) {
      if (typeof obj[property] == "object") {
        if (Object.keys(obj[property]).length === 0) {
          emptyProperties.push(property);
        } else{
          let x = iterate(obj[property]);
          emptyProperties.push(...x);
        }
      } else {
        continue;
      }
    }
  }
  return emptyProperties;
}

var key = iterate(json)
console.log('Key', key);

edited Aug 13, 2018 at 10:09

answered Aug 13, 2018 at 9:45

void

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3 Comments

Dev Over a year ago

Not working for this json var json = { "personInfo": { "personAttributesInfo": { "location": { "city": "New york" } } }, "dataInfo": { "travelPricing": { }, "cost": { "usd": 12345, } } }

void Over a year ago

@JohneDoe see the updated answer with an even more complicated object.

Dev Over a year ago

What is ` emptyProperties.push(...x);` and why we are using array , i need only first encounter empty object not all

Mamun · Accepted Answer · 2018-08-13 09:43:45Z

1

function iterate expects something. You have to return from else

return iterate(obj[property]);

var json = {
      "info": {
      "name": {},
      "addr": {
        "strreet": "NYC",
        "zip": 123456789
       }
     }
   }


function iterate(obj) {
for (var property in obj) {
    if (obj.hasOwnProperty(property)) {
        if (typeof obj[property] == "object") {
            if (JSON.stringify(obj[property]) === '{}') {
                return property
            } else
                return iterate(obj[property]);
        } else {}
    }
}
}


var key = iterate(json)
console.log('Key', key)

answered Aug 13, 2018 at 9:43

Mamun

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5 Comments

Dev Over a year ago

This will not work for nested, for example check this json var json = { "personInfo": { "personAttributesInfo": { "location": { "city": "New york" } } }, "dataInfo": { "travelPricing": { }, "cost": { "usd": 12345, } } }

Dev Over a year ago

It's still returning undefined after code changes suggested by you

Mamun Over a year ago

@JohneDoe, are getting undefined with the input in the comment?

Dev Over a year ago

Yes i'm getting input in the comment

Dev Over a year ago

It should return travelPricing

vincent · Accepted Answer · 2021-01-13 01:10:39Z

This answer uses object-scan.

As indicated as desired by the author in a comment, only the first encounter is returned.

Observations:

object-scan will traverse into nested arrays. If that is not desired one could check !Array.isArray(value) in breakFn.
If performance is important one could separate the compile and search part of object-scan

// const objectScan = require('object-scan');

const isEmptyObject = (value) => (
  value instanceof Object
  && !Array.isArray(value)
  && Object.keys(value).length === 0
);
const finder = (input) => objectScan(['**'], {
  abort: true,
  rtn: 'key',
  filterFn: ({ value }) => isEmptyObject(value)
})(input).pop();

const json = { personInfo: { personAttributesInfo: { location: { city: 'New york', state: {} } } }, dataInfo: { travelPricing: {}, cost: { usd: 12345, someother: {} } } };

console.log(finder(json));
// => someother

.as-console-wrapper {max-height: 100% !important; top: 0}

<script src="https://bundle.run/[email protected]"></script>

Disclaimer: I'm the author of object-scan

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