remove-duplicates-from-array-of-objects.md

Remove the Duplicate Elements from the Array of Objects

const list = [
  { name: 'John' }, 
  { name: 'Sara' },
  { name: 'Sara' },
  { name: 'Lynn' },
  { name: 'Jake' }
];

There are a few ways to do this. Your first intuition might be to do something like this.

const uniqueList = Array.from(new Set(list))

It’s the right idea since creating a Set will ensure our collection only contains unique values and Array.from allows us to create a new, shallow-copied array. Unfortunately, Sets only enforce uniqueness for primitive values, but our list is full of objects.

Instead, we can do something like this.

const map = new Map();

list.forEach(item => {
	map.set(item.name, item)
});

const uniqueList = Array.from(map.values())

Notice we’re using a Map here. Since Map’s preserve insertion order, our uniqueList will have the same order as the original list, but without the duplicates since we’re using name as the key.

Another fancy approach is using filter with findIndex,

const uniqueList = list.filter((item, index) => 
  list.findIndex(({name}) => 
    name === item.name
  ) === index
);

Or using .reduce and .map,

const uniqueList = Object.keys(
  list.reduce((acc, cur) => {
    acc[cur.name] = cur.name;
    return acc;
  }, {}),
).map((name) => ({ name }));

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