Replace object value with other object's value of the same key with JavaScript

Question

I've got two objects, item and results . They've both got the same keys but possibly different values, for example:

item.id = '50'
item.area = 'Mexico'
item.gender = null
item.birthdate = null

results.id = '50'
results.area = null
results.gender = 'Male' 
results.birthdate = null

What I want to do is exactly the following:

if (item.id == null || items.id == 0)
{
    item.id = results.id;
}

but I'm looking for a way to do this for each value of my item object. You know, without having to write a huge function if my objects happen to have a lot more keys / values. Any ideas?

Update : I misunderstood my own problem and the only issue was that I didnt really understand how to get an object value given a certain key. I couldnt really use any outside scripts or divs since Im using Azure's mobile service scripts.

for (var key in item) {
    if(item[key] == null || item[key] == 0){
        item[key] = results[0][key] 
    }             
}

Answer 1

It could do the trick !

 var item = {}; var results={}; item.id = '50' item.area = 'Mexico' item.gender = null item.birthdate = null results.id = '50' results.area = null results.gender = 'Male' results.birthdate = null Object.keys(item).forEach(function(key) { if (item[key] == null || item[key] == 0) { item[key] = results[key]; } }) document.getElementById('dbg').innerHTML ='<pre>' + JSON.stringify(item , null , ' ') + '</pre>'; console.dir(item);

 <div id='dbg'></div>

Answer 2

You can elegantly use lodash :

 var results = {}; var item = {}; item.id = '50'; item.area = 'Mexico'; item.gender = null; item.birthdate = null; results.id = '50'; results.area = null; results.gender = 'Male'; results.birthdate = null; _.merge(results, _.pick(item, _.identity)); alert(JSON.stringify(results));

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

Note that the requested value is now in results (and not in item). If you still need it item, clone the values into a new variable and use it.

Answer 3

You can loop over the object like this. hasOwnProperty tests if it is a property defined by you and not from the base object definition.

for (var key in item) {
   if (item.hasOwnProperty(key)) {
       if (item[key] == null) {
           item[key] = results[key];
       }
   }
}

Answer 4

You can also use the nullish coalescing operator to simplify it a bit.

 var item = { id: '50', area: 'Mexico', gender: null, birthdate: null }; var results={ id: '50', area: null, gender: 'Male', birthdate: null }; Object.keys(item).forEach(function(key) { item[key] = item[key] ?? results[key]; }) document.getElementById('dbg').innerHTML ='<pre>' + JSON.stringify(item , null , ' ') + '</pre>'; console.dir(item);

 <div id='dbg'></div>

Answer 5

Old post but if you search a more recent straightforward solution you can try Object.assign() . Properties in the target object are overwritten by properties in the sources if they have the same key.

const target = { a: 1, b: 2 };
const source = { b: 4, c: 5 };

const returnedTarget = Object.assign(target, source);

console.log(target);
// expected output: Object { a: 1, b: 4, c: 5 }

console.log(returnedTarget);
// expected output: Object { a: 1, b: 4, c: 5 }

Answer 6

You could just iterate all the object keys, and then write assign them on each item:

for (var property in results) {
    if (results.hasOwnProperty(property) && !item[property]) {
        // do stuff
        item[property] = results[property]
    }
}

Answer 7

对于一个班轮，这是一个选项：

{ ...item, ...Object.keys(results).reduce((pv, cv) => results[cv] == null ? pv : { ...pv, [cv]: results[cv] }, {}) };