JSFiddle - React, Tailwind, and code Playground

by Denis Ineshin

HTML

<input type="text" value="123456789" class="test" />

JavaScript

function prettify (num) {
    var n = num.toString();
    var separator = " ";
    return n.replace(/(\d{1,3}(?=(?:\d\d\d)+(?!\d)))/g, "$1" + separator);
}

var $test = $(".test");
var val = $test.prop("value");
$test.prop("value", prettify(val));