JSFiddle - React, Tailwind, and code Playground

HTML

<div id="result"></div>
<div id="result2"></div>

CSS

#result, #result2{
  color:#000;
  font-size:25px;
}

JavaScript

var x = "84654656";
var pattern = new RegExp('^([\+])?[\d]+$');
var pattern2 = /^([\+])?[\d]+$/;

var result = (pattern.test(x))? "da" : "net";
var result2 = (pattern2.test(x))? "da" : "net";

$('#result').text(result);
$('#result2').text(result2);