src/PluginEngine.js
function(name){
        for (var i = 0, len = _pluginList.length ; i < len ; i++){
            var plugin = _pluginList[i];
            if (name === plugin.name) {
                return true;
            }
        }
        return false;
    }
function(name){
        for (var i = 0, len = _pluginList.length ; i < len ; i++){
            var plugin = _pluginList[i];
            if (name === plugin.name) {
                return true;
            }
        }
        return false;
    }
function ( name ) { for ( var i = 0 , len = _pluginList . length ; i < len ; i ++ ) { var plugin = _pluginList [ i ] ; if ( name === plugin . name ) { return true ; } } return false ; }
weather the plugin is exist in plugin's list or not
@param  {String}  name the plugin's name
@return {Boolean}
weather the plugin is exist in plugin s list or not