add a custom button Doclib-ribbon SharePoint Online

Question

I would like to add a custom button on the default Document Library Ribbon. You know, like next to 'new','share','automate','myCostumBtn'

Any of you guys a good suggestion?

Answer 1

As you are using SharePoint Online, I will suggest you to create a ListView Command Set for your document library using SPFx extensions.

Check below official documentations for same:

1. Overview of SharePoint Framework Extensions
2. Build your first ListView Command Set extension

Answer 2

'CommandUI.Ribbon' user custom action is still supported in SP online. Please take a reference of below doc to get started:

• CommandUI.Ribbon user custom actions

Of course SPFx extension is also a good option.

BR