JSFiddle - React, Tailwind, and code Playground
JavaScript
var str = 'Lorem ipsum 234456234 Lorem ipsum 7345287346 asdfae';
document.write('From <strong>'+str+'</strong><br />');
document.write('To <strong>'+str.replace(/(\d)(?=(\d\d\d)+([^\d]|$))/g, ' ')+'</strong>');