In programming terms, proxy is any entity that acts on behalf of some other entity. A proxy server sits in between a client and server and acts a client for server and vice versa. The job of any proxy is to intercept incoming requests/calls and forward it upstream. This interception allows proxy to add logic and change behavior of incoming and outgoing requests.

Javascript proxy is something very similar, it sits between your actual object and the code trying to access this object.

We will look at how to implement a proxy and what are few real world use cases for them in the article Javascript Proxies : Real World Use Cases