N/ui/serverWidget Module
Form.insertSublist()
Method Description: Inserts a sublist in front of another sublist.
Returns: void
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=Form.insertSublist(options)

// Code Example 1

//Add additional code

//...

var form = serverWidget.createForm({

    title : 'Simple Form'

});

var sublist1 = form.addSublist({

    id : 'sublistid1',

    type : serverWidget.SublistType.INLINEEDITOR,

    label : 'Inline Editor Sublist'

});

var sublist2 = form.addSublist({

    id : 'sublistid2',

    type : serverWidget.SublistType.INLINEEDITOR,

    label : 'Inline Editor Sublist'

});

form.insertSublist({

    sublist : sublist2,

    nextsublist : 'sublistid1'

});

//...

//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4340337306.html