JSFiddle - React, Tailwind, and code Playground

HTML

<div id='label'></div>

JavaScript

var er = {
a:"a",
b:"b",
c:"c",
d:"a"
} 

    var arr=[];
    $.map(er, function(value, key){           
        if   ( arr.indexOf(value) == -1 ) 
       {arr.push(value);}
    });
    $('#label').html(arr.join());