How to identify your browser's JavaScript engine

Available for both PC browsers and mobile browsers.

The principle is this js:

window.onload = function() {  
  var v8string = 'function%20javaEnabled%28%29%20%7B%20%5Bnative%20code%5D%20%7D';  
     
  if (window.devicePixelRatio)  //If WebKit browser  
  {  
     if (escape(navigator.javaEnabled.toString()) === v8string)  
     {  
        display('V8 detected');  
     }  
     else 
     {  
        display('JSC detected');  
     }  
  }  
  else {  
    display("Not a WebKit browser");  
  }  
     
  function display(msg) {  
    var p = document.createElement('p');  
    p.innerHTML = msg;  
    document.body.appendChild(p);  
  }  
     
};

First detect the WebKit-specific attribute devicePixelRatio, and then detect the implementation of the v8-specific javaEnabled function.