Hi Ruzic,
Thank you for contacting Syncfusion products.
In Syncfusion’s Essential Studio for JavaScript installed machine, you can find the exporting web API in the below location. We have also provided the user guide documentation link for implementing the exporting option in sample level.
File location:<SystemDrive>:\Users\userName\AppData\Local\Syncfusion\EssentialStudio\x.x.xx\JavaScript\ejservices\webapi\PivotGrid\JSPivotGridExportController.cs
Please let us know if you have any other queries.
Thanks,
Alagarsamy D