How to add custom button in outlook mail page and outlook calendar page using outlook add-ins

In outlook mail , mail read page and calendar page , i want to add a custom button using outlook add-ins manifest file

if i install outlook add-ins this button will be show on that places

Any extension point is there for custom button add , I want trigger some function in outlook add-ins after click that custom buttons

it is possible or not , The outlook mail support for add custom button using outlook add-ins

Note : my outlook add-ins developed using javascript language

please suggest me