check if an object with a specific key value exists in an array of objects

Question

I'm trying to check if an array of items contains an object with a specific key value, and if it does, just update the array of items with the new item object

[{name: example1, quantity: 2},{name: example2, quantity: 3},{name: example3, quantity: 5}]

so if for example I'm pushing an object with the same name of "example1", I want to check if it does exist in the array and if it does, just update it with the new object with the new quantity for example.

I tried to explain what I want as best as I can, please let me know if you need more clarification.

Do these objects only have name and quantity keys? If so, then you should just use a mapping, not an array of objects. If there's more keys in the objects, what would happen to those keys when you merge? — Håken Lid
– Håken Lid, Commented Oct 26, 2018 at 9:55
You should really add a) a before/after example of your array of objects (because, based on the answers, I'm not sure people understand what you want, and b) your own attempted solution. — Andy
– Andy, Commented Oct 26, 2018 at 10:03

cнŝdk · Accepted Answer · 2018-10-26 09:59:56Z

5

You can use a simple combination of Array#some() and Array#find() methods:

if (data.some(o => o.name == toPush.name)) {
  data.find(o => o.name == toPush.name).quantity = toPush.quantity;
}

Where data is your array and toPush is the object you are trying to update.

Demo:

var data = [{
  name: "example1",
  quantity: 2
}, {
  name: "example2",
  quantity: 3
}, {
  name: "example3",
  quantity: 5
}];

let toPush = {
  name: "example2",
  quantity: 10
};

if (data.some(o => o.name == toPush.name)) {
  data.find(o => o.name == toPush.name).quantity = toPush.quantity;
}

console.log(data);

answered Oct 26, 2018 at 9:59

cнŝdk

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2 Comments

Andy Over a year ago

I think this is the only answer that understands the question

cнŝdk Over a year ago

@Andy Thank you, yes, he should check if the searched object exists and updates it.

Mahesh Kumar Maisa · Accepted Answer · 2018-10-26 10:48:07Z

3

let arr1 = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}];
let obj1 = {name: 'example1', quantity: 5};
if(arr1.filter(item=> item.name === obj1.name).length==0){
  arr1.push(obj1);
}
else{
  arr1.filter(item=> item.name === obj1.name)[0].quantity = obj1.quantity;
}

answered Oct 26, 2018 at 10:48

Mahesh Kumar Maisa

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Comments

Ankit Agarwal · Accepted Answer · 2018-10-26 10:04:14Z

2

You can use Array.find() for that update and pushing the unique objects. You can also use existObj = obj; so that all the updated properties of obj is set on the existing object and not just one property (as it is now with quantity). But if you need only the quantity property to get updated then use existObj.quantity = obj.quantity;

let arr = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}];
let obj = {name: 'example1', quantity: 5};
var existObj = arr.find(({name}) => name === obj.name);
if(existObj){
  existObj = obj;
} else {
  arr.push(obj);
}
console.log(arr);

edited Oct 26, 2018 at 10:04

answered Oct 26, 2018 at 9:53

Ankit Agarwal

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Comments

Asif vora · Accepted Answer · 2018-10-26 10:00:10Z

1

I'd use the Array.prototype.some() function:

const arr = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}]


var result = arr.some(e => e.hasOwnProperty('name') && e.hasOwnProperty('quantity'));

console.log("The array contains an object with a 'name' and 'quantity' property: " + result);

answered Oct 26, 2018 at 10:00

Asif vora

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Comments

sdabrutas · Accepted Answer · 2018-10-26 10:01:28Z

1

Better use Array.findIndex() with this

let myArray = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}];
const newItem = { name: 'example1', quantity: 5 };
const indexOfItem = myArray.findIndex(item => item.name === item.name);

if(indexOfItem === -1) { // not existing
  myArray.push(newItem);
else {
  myArray[indexOfItem] = newItem;
}

answered Oct 26, 2018 at 10:01

sdabrutas

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Comments

Nitish Narang · Accepted Answer · 2018-10-26 10:15:59Z

1

You can create "push" function and pass in the object you want to add/update. Function will take care if it needs to add / update arr by using "find". Also, this will take care of all properties not just "quantity"

var arr = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}]

function push(obj) {
  var data = arr.find(({name}) => name == obj.name) || (arr = arr.concat({})).slice(-1)[0];
  Object.assign(data, obj)
}

push({ name: 'example11', quantity: 100 })
console.log('example11 added', arr)

push({ name: 'example1', quantity: 100 })
console.log('example1 updated', arr)

answered Oct 26, 2018 at 10:15

Nitish Narang

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Comments

Beginner · Accepted Answer · 2018-10-26 10:17:00Z

1

you can use Array.forEach which iterates through each object, and we can update existing array with using the index param.

Please see the below code.

var data = [{name: "example1", quantity: 2},{name: "example2", quantity: 3},{name: "example3", quantity: 5}]

var object = {name: "example1", quantity: 14}

data.forEach((o,index) => {
  if(o.name === object.name){
    o.quantity = object.quantity
    return data[index] = o
  }else{
    data[index] = o
  }
})


console.log("updated data array =>", data)

answered Oct 26, 2018 at 10:17

Beginner

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Comments

Nishikant Chavan · Accepted Answer · 2018-10-26 10:15:28Z

0

In case if you want to match both object key & values, this will work.

let myArray = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}];
let newObj = { name: 'example1', quantity: 5 };

let myArrayJSON = JSON.stringify(myArray);
let newObjJSON = JSON.stringify(newObj);

if(myArrayJSON.indexOf(newObjJSON) === -1){
   myArray.push(newObj); 
}

answered Oct 26, 2018 at 10:15

Nishikant Chavan

92 bronze badges

Comments

Мя Рєяғєст · Accepted Answer · 2018-10-26 10:26:59Z

0

var ObjectArray = [{name: 'example1', quantity: 2},{name: 'example2', quantity: 3},{name: 'example3', quantity: 5}]
    console.log(ObjectArray)
   var name = 'example2'
   var index = ObjectArray.findIndex(product => product.name == name);
   if(index>=0){
        console.log("Found and updated ObjectArray")
       ObjectArray.splice(index, 1, {name: 'example2', quantity: 8});
       console.log(ObjectArray)
   }
   else{
      console.log("not found")
   }

edited Oct 26, 2018 at 10:26

answered Oct 26, 2018 at 10:10

Мя Рєяғєст

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1 Comment

Michael McMullin Over a year ago

Welcome to SO! This code might be a good answer, but it would be better to avoid code-only answers and provide some explanation/context.

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