CO3404 Distributed Systems
CO3404 Lecture 3 - REST & Intro to NodeJS

Lecture Documents¶

CO3404 Lecture 4.pdf

Written Notes¶

Learning Objectives¶

• Write named functions, anonymous functions, and arrow functions.
• Write a function that takes another function as a callback parameter.
• Write an anonymous function as a function argument.
• Call an asynchronous asynchronous API functions such setTimeout and fetch.
• Explain the basic operation of code that uses promises
• Create and test a sample node express API application

Function Declaration¶

Many ways to define / declare functions, somewhat due to various browser incompatibilities and some enhancements to the language as it has evolved.

For named functions, the function is moved to the top of the file by the parser if not in a block so it can be called before its declaration.

getData() // can be run before declaration
function getData();

Function Expression¶

A function expression creates an anonymous function and effectively assigns its address to its assigned variable.

getData();
const getData = function() { ... }

The assigned function has only the scope it was defined, which allows more control over clashing functions that share the same name from various libraries.

Arrow Functions¶

CO3404 Lecture 5 - Promises, Middleware & Databases