Functional Programming

• Programming with a distinction between pure code and impure code.
• Pure code has no side effects and gets the same results every time you run it.

Pure functions

• Return a value solely based on what was passed into it.
• Does not mutate data, produces no side effects, and can easily be reused.

Higher order functions

• A function that operates on other functions.

Objects and Inheritance

• JavaScript objects use prototype-based inheritance

Errors

• Important for debugging broken code.

Writing Good Error Messages

• Will have a timestamp, message about problem, message about cause, consistent format, and a severity level.

Handling Thrown Errors

• Forces developers to use a function correctly.
• Unhandled errors will often crash javascript and stop program execution.
• try {} catch (error) {} all servers to run with errors