JSFiddle - React, Tailwind, and code Playground

HTML

<p id="content"></p>

JavaScript

function onlyUnique(value, index, self) { 
    return self.indexOf(value) === index;
}

var a = [3,2,1,1,2,3,1,2,3,1,2,3,3,1,3,1,1,3,2,1,3,2,1,2,3,1,3,2];
var unique = a.filter( onlyUnique );
var elem = document.getElementById('content');
content.textContent = unique;