JSFiddle - React, Tailwind, and code Playground

HTML

<div id="d"></div>

JavaScript

function parse(s) {
    var found = false;
    ['.', ','].forEach(function (el) { 
        var i = s.indexOf(el);
        if (s[i] === s[s.length - 2]) {
            s = s + '0';
            found = true;
            return false;
        }
    });
    if (!found) {
        return s.replace(/(\.|,|\s)/g, '');
    } else {
        return s;
    }
}
document
    .getElementById('d')
    .innerHTML = parse('4.50');