javascript array look for similar object - if not present add to array

Question

I got an array of objects with structure like this

myArr = [
         {name: Test1, age: 20,  info: Test2}, 
         {name: Test2, age: 20, info: Test3},
         {name: Test5, age: 28, info: Test30}
 ]

With my custom action I am adding new info to array. But before adding new obejct into array I want to check if similiar one exist (same values for all keys). If yes - do nothing, if no similar object - add to array.

Simple for loop duplicates objects since it is running over all elements of the array.

var i;
for(i = 0; i < myArr.length; i++) {
    if((myArr[i].name === added.name) && (myArr[i].age === added.age) && (myArr[i].info === added.info) {

    }
    else {
        myArr.push(added);
    }
}

Are you OK with using an external library like LoDash (lodash.com)? That has functions for search an array for matching objects. — kshetline
– kshetline, Commented Mar 9, 2018 at 12:17
@kshetline: So does the JavaScript standard library (as of three years ago). — T.J. Crowder
– T.J. Crowder, Commented Mar 9, 2018 at 12:18
@TJ -- Methods that would match each object in an array with another object, member-by-member, rather than doing a simple === comparison? — kshetline
– kshetline, Commented Mar 9, 2018 at 12:24
@kshetline: Not that specifically, no, but not far off either. For instance: var keys = Object.keys(added); if (!myArr.some(e => keys.every(k => added[k] === e[k]))) { /* ... */ } Throw in Object.keys(e).length === keys.length if you want that check (or tweak in about 18 other ways). — T.J. Crowder
– T.J. Crowder, Commented Mar 9, 2018 at 12:56

T.J. Crowder · Accepted Answer · 2018-03-09 12:20:38Z

The problem is that you're adding within the loop. Instead, you want to add only after the loop if you didn't find a match.

So with minimal changes:

var i;
for(i = 0; i < myArr.length; i++) {
    if((myArr[i].name === added.name) && (myArr[i].age === added.age) && (myArr[i].info === added.info) {
        // Found, stop here
        break;
    }
}
if (i === myArr.length) {
    // Not found, add
    myArr.push(added);
}

But you can also use Array#find (added in ES2015, you can polyfill it for obsolete environments) or Array#some (also added in ES2015):

if (!myArr.find(function(e) { return e.name === added.name && e.age === added.age && e.info === added.info; })) {
    myArr.push(added);
}

It's a bit clearer if you use an ES2015 arrow function:

if (!myArr.find(e => e.name === added.name && e.age === added.age && e.info === added.info)) {
    myArr.push(added);
}

Ishwar Patil · Accepted Answer · 2018-03-09 12:21:24Z

0

Check this. You can use .find() to match your condition and check if it is already present.

myArr = [
         {name: 'Test1', age: 20,  info: 'Test2'}, 
         {name: 'Test2', age: 20, info: 'Test3'},
         {name: 'Test5', age: 28, info: 'Test30'}
 ]
 
let added = {name: 'Test6', age: 22, info: 'Test40'};
 
let matching = myArr.find(a => a.name === added.name && a.age === added.age && a.info === added.info);

if(!matching) {
  myArr.push(added)
  console.log('added');
  console.log(myArr)
}

answered Mar 9, 2018 at 12:21

Ishwar Patil

1,7363 gold badges12 silver badges20 bronze badges

Collectives™ on Stack Overflow

javascript array look for similar object - if not present add to array

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related