JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://dl.dropboxusercontent.com/s/0qp553qax1sa9fk/FileSaver.js?m="></script>

JavaScript

$(function(){   
var blob = new Blob([ "iiiiiii" ], {
                type : "text/plain;charset=utf-8"
            });

          alert(UrlExists('a.txt'))
            saveAs(blob, 'a.txt');
});

function UrlExists(url)
{
    var http = new XMLHttpRequest();
    http.open('HEAD', url, false);
    http.send();
    return http.status!=404;
}