How to combine all unique element in any given array property from array of object into single array in javascript?

Question

I have below javascript array of object problem in which i have tag array property inside array of object. Tag array contain some value in each array of object. I wanted to get unique tag value from each array of object and combine into single array which will contain only unique tag.

const obj = [{
  name: "ABC",
  tag: ["abc", "xyz"]
}, {
  name: "USA",
  tag: ["abc", "suv"]
}, {
  name: "ABC",
  tag: ["pot", "xyz"]
}]

I need the unique tag item into single array as per below.

const unique = ["abc", "xyz", "suv", "pot"];

Answer 1

You could use flatMap and Set

const obj = [
  { name: 'ABC', tag: ['abc', 'xyz'] },
  { name: 'USA', tag: ['abc', 'suv'] },
  { name: 'ABC', tag: ['pot', 'xyz'] },
]

const res = [...new Set(obj.flatMap(({tag}) => tag))];

console.log(res)

Answer 2

A set will give you unique values:

• Set
• Array.prototype.flatMap()
• Spread syntax (...)
• Unpacking properties from objects passed as a function parameter

const obj = [{
  name: "ABC",
  tag: ["abc", "xyz"]
}, {
  name: "USA",
  tag: ["abc", "suv"]
}, {
  name: "ABC",
  tag: ["pot", "xyz"]
}]

const unique = [...new Set(obj.flatMap(({tag}) => tag))];

console.log(unique)

Answer 3

You can use Set to filtered out the unique elements from an array.

Demo :

const obj = [{
  name: "ABC",
  tag: ["abc", "xyz"]
}, {
  name: "USA",
  tag: ["abc", "suv"]
}, {
  name: "ABC",
  tag: ["pot", "xyz"]
}];

let arr = [];

obj.forEach((item) => {
    arr.push(...item.tag)
})

console.log([...new Set(arr)]);