CODEWITHSUNDEEP
javascriptobject
perennial_
perennial_

Reputation: 1846

Replace shared properties of javascript object

I have two javascript objects, which share several properties.

var object1 = {"prop1":"a", "prop2": "b", "prop3":"c"};
var object2 = {"prop2":"d", "prop4": "e", "prop5":"f"};
//replace shared properties here
//maybe using object.hasOwnProperty???
return object1;
//desired output: {"prop1":"a", "prop2": "d", "prop3":"c"};

I would like to use object1 as a template to return a set of filters to my user, however, filters may change, and those changes would be saved to object2. I am trying to update properties in object1 with those in object 2, only if they exist in both objects. In this example, for instance, I want to take default values of prop1 and prop3, use object2's value of prop2, and ignore prop4 and prop5. I could easily loop through the properties of object1 and check if they're in object2, but I feel like there must be an easier way to do this (similiar to union() or intersection())

Upvotes: 2

Views: 62

Answers (3)

Arnauld
Arnauld

Reputation: 6130

You can build your output by iterating on the keys of object1 and using the values of object2 when they exist.

var object1 = {"prop1":"a", "prop2": "b", "prop3":"c"};
var object2 = {"prop2":"d", "prop4": "e", "prop5":"f"};

var output = {};

Object.keys(object1).forEach(function(k) {
  output[k] = (object2[k] === undefined ? object1 : object2)[k];
});

console.log(output);

Upvotes: 2

mash
mash

Reputation: 2526

One way to do it would be:

const object1 = {"prop1":"a", "prop2": "b", "prop3":"c"};
const object2 = {"prop2":"d", "prop4": "e", "prop5":"f"};
for (const key in object1) {
  if (object1.hasOwnProperty(key) && object2.hasOwnProperty(key)) {
    object1[key] = object2[key];
  }
}
console.log(object1);

Upvotes: 1

Kyeotic
Kyeotic

Reputation: 19857

Something like this?

var object1 = {"prop1":"a", "prop2": "b", "prop3":"c"}
var object2 = {"prop2":"d", "prop4": "e", "prop5":"f"}

function mergeCommon (a, b) {
   return Object.keys(a).reduce((obj, prop) => {
     if (prop in b) obj[prop] = b[prop]
     return obj
   }, a)
}

console.log(mergeCommon(object1, object2))

Upvotes: 2

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