javascript run programm and get response when load code example

Example: javascript on script loaded

function loadScript( url, callback ) {
  var script = document.createElement( "script" )
  	  script.type = "text/javascript";
 	  script.onload = function() {
     	callback()
      };
}
// call the function...
loadScript("js/myscript.js", function() {
  alert('script ready!'); 
});