text: window.addEventListener("load", function(){
    var prefix = (Array.prototype.slice
    .call(window.getComputedStyle(document.documentElement, ''))
    .join('') 
    .match(/-(moz|webkit|ms)-/))[1];
  
    // moz - Firefox (Gecko Engine)
    // webkit - Chrome, Safari, Opera (Webkit Engine)
    // ms - Internet Explorer & Edge (Trident Engine)
    // NOTE - Old Opera versions use Presto Engine. Prefix is -o
    console.log(prefix);
  });