Rico 模块加载方式

include : function(filename) {    if (this.loadedFiles[filename]) return;    this.addPreloadMsg('include: '+filename);    var ext = filename.substr(filename.lastIndexOf('.')+1);    switch (ext.toLowerCase()) {      case 'js':        this.loadedFiles[filename]=filename.substring(0,4)=='rico' ? this.loadRequested : this.loadComplete;        document.write("<script type='text/javascript' src='"+this.jsDir+filename+"'><\/script>");        return;      case 'css':        var el = document.createElement('link');        el.type = 'text/css';        el.rel = 'stylesheet';        el.href = this.cssDir+filename;        this.loadedFiles[filename]=this.loadComplete;        document.getElementsByTagName('head')[0].appendChild(el);        return;    }  }