Functions on Coderrob

JavaScript Arrow Functions Explained

Mon, 27 Apr 2026 11:30:00 -0500

Arrow functions are compact JavaScript functions with a few deliberate differences from ordinary functions.

They are excellent for small transformations and callbacks. They are not a universal replacement for function, and treating them like one hides the exact behavior that makes them useful.

Use an arrow when you want a concise function and do not need the function to define its own this, arguments, or constructor behavior.

The Basic Syntax

An ordinary function expression looks like this:

JavaScript 'this' Explained

Mon, 27 Apr 2026 11:00:00 -0500

JavaScript’s this is not difficult because it does many things. It is difficult because one small word changes value based on how a function is called.

That makes this look unpredictable when the real problem is usually that we are looking in the wrong place.

For an ordinary function, do not start with where the function was written. Start with the call-site.

The call usually decides this.

That one rule explains most of the behavior you will meet in day-to-day JavaScript.

JavaScript Closures and Modified Closures Explained

Mon, 27 Apr 2026 10:00:00 -0500

Closures show up any time a JavaScript function uses a variable defined from outside its own curly braces.

That makes them common in callbacks, event handlers, timers, factory functions, and plenty of code that passes functions around.

This post is about two questions:

What is a closure?
What happens when a closed-over variable is modified before the function uses it?

The short version:

A closure happens when a function keeps access to variables from its surrounding scope, even after that outer scope has finished running.

JavaScript Function Parameters and Arguments Explained

Thu, 17 Sep 2020 00:46:15 -0500

JavaScript Function Signatures

Alright, you’ve probably seen functions before. Something like this maybe?

 function doSomething(name, desc, task) {
 // did something
 }

This function, named doSomething, takes three parameters as part of its function signature. These parameters named name, desc, and task are the names of the values being sent into the function.

I’m going to use a sportsball reference here so be warned. You can think of the function as a net that gets various types of objects tossed into the hoop ( ) where it triggers sports points.