JSFiddle - React, Tailwind, and code Playground

JavaScript

function checkForDupes(arr){
    for(var i = arr.length - 1; i >= 0; i--){
        if(arr.indexOf(arr[i]) !== i){
            arr.splice(i,1);
        }
    }
    return arr;
}

var list =[1,2,3,3,4,43,43,4,32,23,3,2,3,4,4,65,87,79,89,78,76,67];

list = checkForDupes(list);

alert(list);