Combine Object/Array using Vanilla JS-CodePudding

How do you combine two objects like this?

const target = { year1 : {}, year2: {somevalue2...}};
const source = { year1 : {somevalue1...}, year2: {} };

expected Input:

{ year1 : {somevalue1}, year2 : {somevalue2} }

Thank you!

CodePudding user response：

Use lodash _.merge

const target = { year1 : {}, year2: {s:1}}
const source = { year1 : {s:2}, year2: {} }
const result = _.merge(target, source);
console.log('result', result)
// => { year1 : {s:2}, year2: {s:1}}

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>

CodePudding user response：

You can use nested Array#reduce a way to look at {} as null as in the following demo:

const target = { year1 : {}, year2: {somekey2:"somevalue2"}};
const source = { year1 : {somekey1:"somevalue1"}, year2: {} };

//A function to convert any {} to null
const e2Null = obj => 
  obj && 
  Object.keys(obj).length === 0 && 
  obj.constructor === Object ? 
  null : obj;

const output = [source,target]
    .reduce((acc,cur) => Object.keys(cur)
        .reduce((a,c) => ({...a,[c]:acc[c] ?? e2Null(cur[c])}), {}),{}
    );

console.log( output );

Alternatively, you can use jQuery's .isEmptyObject(...) method as follows:

const target = { year1 : {}, year2: {somekey2:"somevalue2"}};
const source = { year1 : {somekey1:"somevalue1"}, year2: {} };

const e2Null = obj => jQuery.isEmptyObject(obj) ? null : obj

const output = [source,target]
    .reduce((acc,cur) => Object.keys(cur)
        .reduce((a,c) => ({...a,[c]:acc[c] ?? e2Null(cur[c])}), {}),{}
    );
    
console.log( output );

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

CodePudding user response：

You can recursively iterate over all the properties of target and source using Object.entries() or Object.keys(), and copy the properties that you want to the source or to a new object.

Something like that:

const combine = (target, source) => {
  for(const [key, value] of Object.entries(source)) {
    // here you copy the `value` to `target[key]` or
    // if the value is an object you can call `combine()` recursively
    // on the `value` and `target[key]`
  }
}