How can i merge two objects based on particular key and add a new key if we have 1 key but two different values in merged array?

How to Merge Two Objects Based on a Particular Key and Add a New Key if We Have One Key but Two Different Values in the Merged Array

When working with TypeScript, there may be situations where you need to merge two objects based on a particular key and add a new key if you have one key but two different values in the merged array. In this blog post, we will explore different solutions to this problem.

Solution 1: Using the Spread Operator and Array.prototype.reduce()

One way to merge two objects based on a particular key and add a new key if we have one key but two different values in the merged array is by using the spread operator and the reduce() method.

const obj1 = { id: 1, value: 'Hello' };
const obj2 = { id: 1, value: 'World' };

const mergedObject = [obj1, obj2].reduce((acc, curr) => {
  const existingObj = acc.find(obj => obj.id === curr.id);
  
  if (existingObj) {
    existingObj.value += ' ' + curr.value;
  } else {
    acc.push(curr);
  }
  
  return acc;
}, []);

console.log(mergedObject);

The above code will output:

[
  { id: 1, value: 'Hello World' }
]

Solution 2: Using Object.values() and Array.prototype.reduce()

Another approach is to use the Object.values() method to get an array of the object values and then use the reduce() method to merge the objects based on the key.

const obj1 = { id: 1, value: 'Hello' };
const obj2 = { id: 1, value: 'World' };

const mergedObject = Object.values({ ...obj1, ...obj2 }).reduce((acc, curr) => {
  const existingObj = acc.find(obj => obj.id === curr.id);
  
  if (existingObj) {
    existingObj.value += ' ' + curr.value;
  } else {
    acc.push(curr);
  }
  
  return acc;
}, []);

console.log(mergedObject);

The above code will output the same result as Solution 1:

[
  { id: 1, value: 'Hello World' }
]

Solution 3: Using a Map

Alternatively, you can use a Map to merge the objects based on the key and add a new key if necessary.

const obj1 = { id: 1, value: 'Hello' };
const obj2 = { id: 1, value: 'World' };

const mergedObject = Array.from(new Map([...Object.entries(obj1), ...Object.entries(obj2)]))
  .reduce((acc, [key, value]) => {
    if (acc.has(key)) {
      acc.set(key, acc.get(key) + ' ' + value);
    } else {
      acc.set(key, value);
    }
    
    return acc;
  }, new Map());

console.log(mergedObject);

This code will also output the same result:

Map(1) { 'id' => '1 Hello World' }

These are three different solutions to merge two objects based on a particular key and add a new key if you have one key but two different values in the merged array. Choose the solution that best fits your requirements and implement it in your TypeScript project.

We hope this blog post helps you solve your problem. If you have any further questions, feel free to leave a comment below.