From 03f03ff47157093e9ea1289ced147587196c18b3 Mon Sep 17 00:00:00 2001
From: Dave Smith-Hayes <me@davesmithhayes.com>
Date: Wed, 9 Oct 2024 21:17:08 -0400
Subject: [PATCH] Add a blog post about JS scope.

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 posts/scope-with-javascript.md | 76 ++++++++++++++++++++++++++++++++++
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 create mode 100644 posts/scope-with-javascript.md

diff --git a/posts/scope-with-javascript.md b/posts/scope-with-javascript.md
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+---
+title: JavaScript Scoping 
+description: A blog post talking about how JavaScript handles scoping
+date: 2024-08-11
+tags:
+  - development
+  - javascript
+  - typescript
+slug: javascript-scoping
+draft: true
+---
+
+## The EventEmitter Class
+
+The other day I was reading through the Types file of the MariaDB JavaScript
+library (since its the better MySQL library for Node.js), and I noticed that
+the `PoolConnection` class _actually_ extends the `EventEmitter` class from
+Node.js. That in and of itself isn't that exciting, but it had me thinking
+about the utility of extending that particular class, and how the scopeing of
+the code used in that class would actually work.
+
+I never put a lot of thought into it, but if you have used the `EventEmitter`
+class in JavaScript at any point in your life, you know that you can attach
+callbacks to events that will be run when that particular event is emitted.
+
+```javascript
+import EventEmitter from "node:events";
+
+const em = new EventEmitter();
+em.on("home-event", function () {
+    console.log("Something happened.");
+});
+
+em.emit("some-event");
+```
+
+When you call `em.emit("some-event")` anywhere this `EventEmitter` exists in
+code, you will get a console log from inside that function. Okay, makes sense,
+so what's interesting about this?
+
+Well the scope of the callback function actually ineherits the called method's
+properties and methods. This can get really interesting if you are extending
+the functionality of the `EventEmitter` class - like in the MariaDB module's
+`PoolConnection` class.
+
+## Getting In-Depth with Scope
+
+So say we had a class that extends the `EventEmitter` class and had some
+methods with some state we cared about in the callback. In the MariaDB context
+that could be anything that has to do with the connection pool - like maybe
+how many open connections are available. We can sketch this out in a very
+trivial class example in TypeScript.
+
+```typescript
+import EventEmitter from "node:events";
+
+class SomePool extends EventEmitter {
+    private freeConnections: number;
+
+    public constructor() {
+        super();
+        this.freeConnections = 4;
+    }
+
+    public getFreeConnectionCount(): number {
+        return this.freeConnections;
+    }
+} 
+```
+
+So now, in any callback function* we can get the total number of free
+connections in the `SomePool` class.
+
+```typescript
+title=
+```