Keep only difference between two JSON

Question

I have a JSON version of a DOM tree and I want keep only the difference between pages (remove nav footer ...)

Example:

const a = {
    id: '1',
    child: [
        {
            id: '2',
            child: [{id: '1'}, {id: '2'}]
        },
        {
            id: '3',
            child: [{id: '1'}, {id: '5'}]
        }
    ]
};

And

const b = {
    id: '1',
    child: [
        {
            id: '2',
            child: [{id: '1'}, {id: '4'}]
        },
        {
            id: '3',
            child: [{id: '1'}, {id: '4'}]
        }
    ]
};

With a function

diff(a, b)

This result

{
    id: '1', 
    child: [
        {
            id: '2', 
            child: [{id: '2'}]

        },
        {
            id: '3', 
            child: [{id: '5'}]
        }
    ]
}

I created this based on recursive function

const diff = (a, b) => {
  if (Array.isArray(a)) {

  }

  if (typeof a === 'object') {
    // ...
    extract(a.child, b.child);
  }
}

How do I do this? Is there an npm package? or with JSON Path? I want to create a function that remove the equal 'parts' between two JSON files with the output of the function having the same structure, but without the 'equal parts' only difference.

That's not JSON. JSON is a *textual notation* for data exchange. [(More here.)](http://stackoverflow.com/a/2904181/157247) If you're dealing with JavaScript source code, and not dealing with a *string*, you're not dealing with JSON. — T.J. Crowder, Oct 19 '17 at 21:04

score 0 · Answer 1 · answered Oct 19 '17 at 21:03

You can do this a little differently, this should get you the right values.

function diff(obj1, obj2) {
  var ret = {};
  for(var i in obj2) {
    if(!obj1.hasOwnProperty(i) || obj2[i] !== obj1[i]) {
      ret[i] = obj2[i];
    }
  }
  return ret;
};

See the code here with your example data https://jsbin.com/toboto/edit?js,console

This solution is not recursive though. Alternatively, for a deep difference I recommend checking out this library https://github.com/flitbit/diff

Keep only difference between two JSON

1 Answers1