Unique List in JavaScript - Cun Yang

Unique List in JavaScript

Unique List in JavaScript

Method 1: Extend native `Array` with `prototype` objects

Array.prototype.addUnique = function(newItem) {
  if (this.includes(newItem)) {
    return;
  }
  this.push(newItem);
}

const names = [];
const uniqueNames = [];

names.push('cun');
names.push('cun');

uniqueNames.addUnique('cun');
uniqueNames.addUnique('cun');

console.log(names);
// with print: [ 'cun', 'cun' ]
console.log(uniqueNames);
// with print: [ 'cun' ]

Note:

Must use function (newItem) {}, not anonymous function (newItem) => {}.

Method 2: From ES6/ES2015, we can using `Set`

const set = new Set();
set.add('cun');
set.add('cun');

console.log(set);
// with print: Set { 'cun' }

References

https://stackoverflow.com/questions/1960473/get-all-unique-values-in-a-javascript-array-remove-duplicates