JSFiddle - React, Tailwind, and code Playground

JavaScript

let arr = [1, 2, 3, 4, 1, 2, 3];

const getUnique = (arr) => {
	return Array.from(new Set(arr));
}

const getUniqueAlt = (arr) => {
	return arr.reduce((acc, cur) => {
  	if(acc.indexOf(cur) == -1) {
    	acc.push(cur);
    }

    return acc;
  }, [])
}

console.log(getUnique(arr))
console.log(getUniqueAlt(arr));