mainfest.json 如何执行函数？

    "plus": {  
        "launchwebview": {  
            "navigationbar": {  
                "titletext": "下载",  
                "titlecolor": "#000000",  

                            "buttons":[  
                            {"color":"blue","float":"left","fontSrc":"./fonts/webdings.ttf","text":"d","onclick":"statusbtn()"},  
                            {"color":"green","text":"搜","float":"right","onclick":"statusbtn()"},  
                            {"color":"green","text":"下","float":"right","onclick":"statusbtn()"}  
                            ]//标题栏上的自定义按钮 详情看 WebviewCustomButtonStyles                                       
            },  

这里不管怎么写 statusbtn 都不执行，应该如何写才能执行？