JSFiddle - React, Tailwind, and code Playground

JavaScript

var someArray = [3,3,3,3,3,3,4,4,4,4,1,1,1,1,1,2,2];

    function cleanArray(oldArray) {
        var newArray = [];
        for(i=0;i<oldArray.length;i++) {
            if( $.inArray(oldArray[i], newArray) == -1 ) {
                newArray.push(oldArray[i]);         
            }
        }
        return newArray;
    }

    document.write(cleanArray(someArray));