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

• imvain2: 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
• Fazila: 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.

Answer 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 } } }
))

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