JSFiddle - React, Tailwind, and code Playground
HTML
<input class="price" id="price">
JavaScript
var = price.toString().replace(/(\d)(?=(\d{3})+$)/g, '$1 ');
<input class="price" id="price">
var = price.toString().replace(/(\d)(?=(\d{3})+$)/g, '$1 ');