N/ui/serverWidget Module
List.addButton()
Method Description: Adds a button to a list.
Returns: serverWidget.Button object
Supported Script Types: SuiteScript 2.0 Suitelet Script Type and SuiteScript 2.0 User Event Script Type (beforeLoad(scriptContext))
Governance: None
Module: N/ui/serverWidget Module
Since: 2015.2
Search NetSuite - https://system.netsuite.com/app/help/helpcenter.nl?search=List.addButton(options)

// Code Example 1

//Add additional code

//...

var list = serverWidget.createList({

    title : 'Simple List'

});

list.addButton({

    id : 'buttonid',

    label : 'Test'

}));

//...

//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4340555101.html