SP.FieldMultiLineText.appendOnly property (sp.js)
Gets or sets a value that specifies whether all changes to the value of the field are displayed in list forms.
Applies to: apps for SharePoint | SharePoint Foundation 2013 | SharePoint Server 2013
var value = SP.FieldMultiLineText.get_appendOnly ()
var value = SP.FieldMultiLineText.set_appendOnly ()
Return value
Type: Boolean