CODEWITHSUNDEEP
javascriptlodash
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Reputation: 693

add an object to an array if it doesn't have the same key with one of the objects in the array

I'm using Lodash. I have the array below:

const array = [{id:1,name:a},{id:2,name:b},{id:3,name:c},{id:4,name:d},{id:5,name:e}];

and I'm about to add another object to this array but before that, I need to check if the new object's name is already in the array or not and if there is one with the name I won't add the new object anymore. I know some ways to do it, for instance, a loop with _.map, but want to make sure if there is an easier way.

Upvotes: 0

Views: 392

Answers (4)

Akrion
Akrion

Reputation: 18515

Doing this with lodash is few chars shorter but here is how you could do it with ES6 and Array.some:

const array = [{ id: 1, name: "A" }, { id: 2, name: "B" }, { id: 3, name: "C" }, { id: 4, name: "D" }, { id: 5, name: "C" }];

const maybeUpdate = (arr, obj) => {
  if(!array.some(x => x.id == obj.id))
    array.push(obj)
}

maybeUpdate(array, {id: 2, name: "F"})   // id exists wont insert
maybeUpdate(array, {id: 12, name: "F"})  // will insert

console.log(array)

Same idea with lodash and _.some would be:

const array = [{ id: 1, name: "A" }, { id: 2, name: "B" }, { id: 3, name: "C" }, { id: 4, name: "D" }, { id: 5, name: "C" }];

const maybeUpdate = (arr, obj) => {
  if(!_.some(array, {id: obj.id}))
    array.push(obj)
}

maybeUpdate(array, {id: 2, name: "F"})   // id exists wont insert
maybeUpdate(array, {id: 12, name: "F"})  // will insert

console.log(array)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

Note that you could also use various other ways to get the same result. Array.find or _.find would work as well since all you have to do is to check if there was a hit:

const maybeUpdate = (arr, obj) => {
  if(!_.find(array, {id: obj.id})) // or if(!array.find(x => x.id == obj.id))
    array.push(obj)
}

Upvotes: 0

slider
slider

Reputation: 12990

You don't need lodash for some. You get that with native JS too (ES6):

const array = [{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'},{id:4,name:'d'},{id:5,name:'e'}];

console.log(array.some(e => e.name === 'a'));

if (!array.some(e => e.name === 'z')) {
  array.push({id: 5, name: 'z'});
}

console.log(array);

Upvotes: 0

brk
brk

Reputation: 50291

With native javascript , you can use findIndex, this will return the index of the object where the name matches. If it returns -1 then there is no such object with same name. In that case update the array.

const array = [{
  id: 1,
  name: 'a'
}, {
  id: 2,
  name: 'b'
}, {
  id: 3,
  name: 'c'
}, {
  id: 4,
  name: 'd'
}, {
  id: 5,
  name: 'e'
}];

let newObjToAdd = {
  id: 1,
  name: 'z'
};
let newObjNotToAdd = {
  id: 1,
  name: 'a'
}


function updateArray(obj) {
  let k = array.findIndex((item) => {
    return item.name === obj.name;
  })
  if (k === -1) {
    array.push(obj)
  } else {
    console.log('Array contains object with this name')
  }
}

updateArray(newObjToAdd);
console.log(array)
updateArray(newObjNotToAdd);

Upvotes: 0

jordrake
jordrake

Reputation: 530

You could use Lodash's some which if provided with an appropriate predicate e.g. (item => item.name === newName) will return a boolean indicating whether or not the item already exists (in this case, true would mean the name already exists). The benefit of using this over other iterating methods is that it will stop as soon as it finds one that returns true resulting in better performance.

Upvotes: 2

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