对象设置默认属性

  const menuConfig = {
        title:null,
        body:'Bar',
        buttonText:null,
        cancellable:true
    };
    function createMenu(config){
        config.title=config.title || 'Foo';
        config.body = config.body || 'Bar';
        config.buttonText = config.buttonText || 'Baz';
        config.cancellable = config.cancellable !== undefined ? config.cancellable : true;
        console.log(config);
    }
    createMenu(menuConfig);