Why can't you use it as a custom module, like moment?

When you upload a client script or add one to a form using

form.clientScriptModule(Id/Path)

the NetSuite server statically analyzes and all the dependencies imported in the

define

array. The SweetAlert library uses

WeakMap

which is a newer JS API that is supported in most browsers but is not recognized by the server, so the server rejects any client script that imports it using

define

.