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.

Answer 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)

Answer 2

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);

Answer 3

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/object-scan@13.8.0"></script>

Disclaimer : I'm the author of object-scan