ELCKEditorAPI = function() {
  this.loadScript = function(url, checkLoaded, callback) {
    if (checkLoaded && checkLoaded())
      return callback && callback();

    var script = document.createElement("script");
    script.type = "text/javascript";
    script.async = true;

    if (script.readyState) {
      script.onreadystatechange = function () {
        if (script.readyState == "loaded" || script.readyState == "complete") {
          script.onreadystatechange = null;
          callback && callback();
        }
      }
    } else {
      script.onload = function() {
        callback && callback();
      }
    }
    
    script.src = url;
    document.head.appendChild(script);
  }
}