Merging JavaScript objects in an array where data matches

Question

I have an array of objects, where I'd like to merge some objects if certain data matches. Here is the array:

0: {name: "1", qty: "3", measurement: "Tbsp"}
1: {name: "paprika", qty: "2", measurement: "Tbsp"}
2: {name: "onion", qty: "1", measurement: "cup"}
3: {name: "tomatoes", qty: "16", measurement: "oz"}
4: {name: "tomatoes", qty: "16", measurement: "oz"}

I'd like to match based on the name and measurement keys. I.e. if the name is the same AND the measurement is the same, then combine the object and total the qty, where the resulting object would be:

0: {name: "1", qty: "3", measurement: "Tbsp"}
1: {name: "paprika", qty: "2", measurement: "Tbsp"}
2: {name: "onion", qty: "1", measurement: "cup"}
3: {name: "tomatoes", qty: "32", measurement: "oz"}

I've tried it a few ways using .includes() and .some() but haven't managed with any success yet. Any help appreciated.

Nick · Accepted Answer · 2020-08-15 23:33:34Z

1

This is a good use case for the array reduce method. The following can be used to determine if our accumulator already has the desired item. If so, add the quantity. If not, push the item onto the accumulator array.

const items = [
  {name: "1", qty: 3, measurement: "Tbsp"}, 
  {name: "paprika", qty: 2, measurement: "Tbsp"},
  {name: "onion", qty: 1, measurement: "cup"},
  {name: "tomatoes", qty: 16, measurement: "oz"},
  {name: "tomatoes", qty: 16, measurement: "oz"}
];

const combined = items.reduce((acc, el) => {
  const found = acc.find(item => item.name === el.name && item.measurement === el.measurement);
  if (found) {
    found.qty += el.qty;
  } else {
    acc.push(el);
  }
  return acc;
}, []);

console.log(combined);

answered Aug 15, 2020 at 23:33

Nick

16.7k3 gold badges21 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

acd37 Over a year ago

This solved my problem excellently. Thank you so much!

charlietfl · Accepted Answer · 2020-08-16 00:43:10Z

0

Approach using a Map and concatenating the name and measurement to create the unique keys so they look like "tomatoes|oz"

const groupItems = (arr) => {
  const m = new Map;      
  arr.forEach(o => {
      const k = `${o.name}|${o.measurement}`;
      // if the key already exists just add current qty 
      // otherwise set new entry using current object
      m.has(k) ? m.get(k).qty += o.qty : m.set(k, {...o});
  });      
  return [...m.values()];
}

console.log(groupItems(data))

<script>
const data=[{name:"1",qty:3,measurement:"Tbsp"},{name:"paprika",qty:2,measurement:"Tbsp"},{name:"onion",qty:1,measurement:"cup"},{name:"tomatoes",qty:16,measurement:"oz"},{name:"tomatoes",qty:16,measurement:"oz"}];
</script>

edited Aug 16, 2020 at 0:43

answered Aug 16, 2020 at 0:07

charlietfl

172k14 gold badges125 silver badges154 bronze badges

Collectives™ on Stack Overflow

Merging JavaScript objects in an array where data matches

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related