In this recipe, we will see how to write server stored JavaScript similar to stored procedures in relational databases. This is a common use case where other pieces of code require access to these common functions and we have them in one central place. To demonstrate server-side scripts, the function will simply add two numbers.
There are two parts to this recipe. First, we see how to load the scripts from the collections on the client-side JavaScript shell and secondly, we will see how to execute these functions on the server.
Note
The documentation specifically mentions that it is not recommended to use server-side scripts. Security is one concern though if the data is not properly audited and hence we need to be careful with what functions are defined. Since Mongo 2.4, the server-side JavaScript engine is V8, which can execute multiple threads in parallel as opposed to the engine prior to version 2.4 of Mongo, which executes only one thread at a time.