N/ui/serverWidget Module
Sublist.lineCount
Property Description: The number of line items on a sublist. The first line number on a sublist is 0 (not 1).
Type: number (read-only)
Supported Script Types: SuiteScript 2.0 Suitelet Script Type and SuiteScript 2.0 User Event Script Type (beforeLoad(scriptContext))
Module: N/ui/serverWidget Module
Since: 2015.2
Search NetSuite - https://system.netsuite.com/app/help/helpcenter.nl?search=Sublist.lineCount

// Code Example 1

//Add additional code

//...

var form = serverWidget.createForm({

    title : 'Simple Form'

});

var sublist = form.addSublist({

    id : 'sublist',

    type : serverWidget.SublistType.INLINEEDITOR,

    label : 'Inline Editor Sublist'

});

var numLines = sublist.lineCount;

//...

//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_452748962402.html