Recursive functions for nested objects in javascript

Question

I know this is some really badly written code so any help would be appreciated. I need to return the values of an object and apply the if statements to any nested objects - is it possible to do this recursively rather than repeating the function?

The code is:

function fusion(x, y) {
    var result = {};

    //y = ifMissingInY(x, y)

    Object.keys(x).forEach(key => {
        //console.log(y.hasOwnProperty(key))
        if (y.hasOwnProperty(key) == true) {
            if (x[key] instanceof Array && y[key] instanceof Array) {
                result[key] = x[key].concat(y[key]);
            } else if (typeof (x[key]) == 'number' && typeof (y[key]) == 'number') {
                result[key] = x[key] + y[key]
            } else if (typeof (x[key]) == 'string' && typeof (y[key]) == 'string') {
                result[key] = x[key] + ' ' + y[key]
            } else if (typeof (x[key]) == 'object' && typeof (y[key]) == 'object') {
                Object.keys(x[key]).forEach(key => {
                    fusion.apply(x[key], y[key])
                });


               } else if (typeof (x[key]) !== typeof (y[key])) {
                result[key] = y[key]
            }
        } else {
            result[key] = x[key]
        }
    });

    Object.keys(y).forEach(key => {
        if (x.hasOwnProperty(key) == false) {
            result[key] = y[key]
        }

    })

    return result;
}

I'm testing against this:

console.log(fusion(
    { a: { b: [1, 2], c: { d: 2 } } },
    { a: { b: [0, 2, 1], c: { d: 23 } } }
))

And it needs to return:

{ a: { b: [1, 2, 0, 2, 1], c: { d: 25 } } }

Any help would be much appreciated.

Thanks

So your code IS working, but you would like to change it? I wonder if codereview.stackexchange.com would be the better site for it — imvain2
– imvain2, Commented Jun 22, 2022 at 22:16
No the code works for strings, array, numbers but not for object it is returning b: [1, 2, 0, 2, 1] rather than {a: {b: ...} and the only way I can make it work is by repeating the function again in the if object which is really messy. — Fazila
– Fazila, Commented Jun 22, 2022 at 22:19

IT goldman · Accepted Answer · 2022-06-22 22:20:08Z

1

You almost got it. Check out the recursion part, it makes sense (once it's written)

function fusion(x, y) {
    var result = {};

    //y = ifMissingInY(x, y)

    Object.keys(x).forEach(key => {
        //console.log(y.hasOwnProperty(key))
        if (y.hasOwnProperty(key) == true) {
            if (x[key] instanceof Array && y[key] instanceof Array) {
                result[key] = x[key].concat(y[key]);
            } else if (typeof (x[key]) == 'number' && typeof (y[key]) == 'number') {
                result[key] = x[key] + y[key]
            } else if (typeof (x[key]) == 'string' && typeof (y[key]) == 'string') {
                result[key] = x[key] + ' ' + y[key]
            } else if (typeof (x[key]) == 'object' && typeof (y[key]) == 'object') {
                
                    result[key] = fusion(x[key], y[key])
                


               } else if (typeof (x[key]) !== typeof (y[key])) {
                result[key] = y[key]
            }
        } else {
            result[key] = x[key]
        }
    });

    Object.keys(y).forEach(key => {
        if (x.hasOwnProperty(key) == false) {
            result[key] = y[key]
        }

    })

    return result;
}

console.log(fusion(
    { a: { b: [1, 2], c: { d: 2 } } },
    { a: { b: [0, 2, 1], c: { d: 23 } } }
))

answered Jun 22, 2022 at 22:20

IT goldman

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3 Comments

Fazila Over a year ago

Thank you so much!! I've been trying to figure it out for the past few hours and couldn't get it to work really appreciate this!

IT goldman Over a year ago

You're welcome. I was lucky to nail it first time, but I did write some recursions in my life. like function extend(obj_a, obj_b) which is the same idea.

Fazila Over a year ago

I understand the concept of recursion but writing the code for it is a whole other matter. Thanks again for your help :)

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