Creating a record using Rest Endpoint from External Application

Hello,

Im a new bee to this CRM world.

I want to perform CRUD operations on an entity from an external application which is completely based on Jquery/Javascript.

I googled and tried few examples but in vain.

First of all, can we perform CRUD operations on an entity completely from javascript ?

If Yes then Is there any scripts that I need to refer for CRM Development?

Experts please guide me through this process.

Thanks