Iterate through an object which has nested objects in nodeJs

Question

I have a javascript object with multiple nested objects like this :

 var stats = {
     bookServed: {
         redis: 90,
         s3: 90,
         signedUrl: 70
     },
     errors: {
         redis: {
             bookService: 70,
             mapi: 50,
             capi: 30
         },
         AWS: {
             signedUrl: 70,
             downloadBook: 50,
             searchBook: 10
         },
         decryption: 60
     }
 };

What would be the cleanest way to iterate through all its properties and set each value to 0 for instance. I wrote something like this

 for (var property in stats) {
     if (stats.hasOwnProperty(property)) {
         if (typeof property === "object") {
             for (var sub_property in property)
                 if (property.hasOwnProperty(sub_property)) {
                     sub_property = 0
                 }
         } else {
             property = 0;
         }
     }
 }

I'm willing to use a library like underscore.js to do the task properly.

Any library you use is going to use a similar method of recursive looping. I assume what you have works, and you're just looking for something... "cleaner" (whatever that means)? — user400654
– user400654, Commented Oct 13, 2015 at 20:58
My solution works only for 2 levels of nested objects, in my example I have 3 level, that's why I want something recursive that go to the deepest level no matter how many levels I have in my object. — Amaynut
– Amaynut, Commented Oct 13, 2015 at 21:01
so make a function that does the step, and if an object is found instead of a number, call the function again on the sub object. — user400654
– user400654, Commented Oct 13, 2015 at 21:02
"and if an object is found instead of a number, call the function again on the sub object." that would make it recursive. — user400654
– user400654, Commented Oct 13, 2015 at 21:06

user400654 · Accepted Answer · 2015-10-13 21:08:26Z

7

Relatively simple recursion problem, I would use a function that calls itself when sub objects are found. I would also avoid using a for in loop, and instead use a forEach on the object's keys (it's much faster, and doesn't require a hasOwnProperty check.)

function resetValuesToZero (obj) {
    Object.keys(obj).forEach(function (key) {
        if (typeof obj[key] === 'object') {
            return resetValuesToZero(obj[key]);
        }
        obj[key] = 0;
    });
}

var stats = {
     bookServed: {
         redis: 90,
         s3: 90,
         signedUrl: 70
     },
     errors: {
         redis: {
             bookService: 70,
             mapi: 50,
             capi: 30
         },
         AWS: {
             signedUrl: 70,
             downloadBook: 50,
             searchBook: 10
         },
         decryption: 60
     }
 };

console.log(stats.errors.AWS.signedUrl); // 70
resetValuesToZero(stats);
console.log(stats.errors.AWS.signedUrl); // 0

answered Oct 13, 2015 at 21:08

user400654

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2 Comments

user400654 Over a year ago

Note that if the object is extremely deeply nested, this could throw a stack overflow exception, but I'd consider that to be very much an edge case. To overcome that, you would need to make this function asynchronous, but I wouldn't bother with that unless you actually ran into that problem, as it definitely complicates things a bit.

vincent Over a year ago

Posted an answer that uses the iterative approach rather than recursion. Also not that this answer will traverse into arrays (it is not clear from the question if that is intended).

vincent · Accepted Answer · 2021-01-13 01:10:52Z

The below solution uses object-scan, which uses an iterative implementation to traverse the input. Also note that this will traverse into any array structures similar to the accepted answer.

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

const rewriter = objectScan(['**'], {
  rtn: 'count',
  filterFn: ({ value, parent, property }) => {
    if (typeof value === 'number') {
      parent[property] = 0;
      return true;
    }
    return false;
  }
});

const stats = { bookServed: { redis: 90, s3: 90, signedUrl: 70 }, errors: { redis: { bookService: 70, mapi: 50, capi: 30 }, AWS: { signedUrl: 70, downloadBook: 50, searchBook: 10 }, decryption: 60 } };

console.log(rewriter(stats)); // returns count of replaces
// => 10

console.log(stats);
/* =>
{ bookServed: { redis: 0, s3: 0, signedUrl: 0 },
  errors:
  { redis: { bookService: 0, mapi: 0, capi: 0 },
    AWS: { signedUrl: 0, downloadBook: 0, searchBook: 0 },
    decryption: 0 } }
*/

.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

LILBRICK1337 · Accepted Answer · 2020-12-18 14:20:14Z

function checkNPE(obj) {
  for(const name in obj){console.log('name: ' + JSON.stringify(name, null, 4));
    if (typeof obj[name] === 'object') {console.log('object name: ' + JSON.stringify(name, null, 4));
      checkNPE(obj[name]);
    } // if (typeof obj[name] === 'object') {
  } // for(const name in obj){
}; // function checkNPE (obj) {

var stats = {
     bookServed: {
         redis: 90,
         s3: 90,
         signedUrl: 70
     },
     errors: {
         redis: {
             bookService: 70,
             mapi: 50,
             capi: 30
         },
         AWS: {
             signedUrl: 70,
             downloadBook: 'a',
             searchBook: 10
         },
         decryption: 60
     }
 };
checkNPE(stats);

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