Inspect the home page for find the App version for downloading supported Extension tool
if used App version – 2021.2.0.108 then
supported extension version is Extension Development Tools -21.2.x.zip from the bundle version is SuiteBundles/Bundle 390093/.
Download the .zip file you find there:
go to root file Run
1. npm install
2.gulp Extension:fetch
3.create Extension
gulp extension:create
set Extension FatacyName: (use our extension name)
vender name: JJ(should be this format)
initial module name :(which pages use for extension)
select necessary JavaScript saas and template etc..