Memory, references, and garbage collection

What this means

Objects are accessed through references and become collectible when no reachable code can use them.

In beginner terms, this topic answers one practical question: "What should I write, and why does React care about it?" Do not try to memorize the syntax first. First understand the idea, then connect the syntax to that idea.

Why it matters

Understanding reachability helps prevent accidental retention through caches, listeners, and closures.

When you build real React screens, this idea helps you decide where data should live, what the user should see, and what should happen after an interaction. That is why this lesson is part of the main path instead of being an optional detail.

Step by step

1. Notice the UI problem this topic solves. 2. Look at the smallest possible example. 3. Change one value and predict what should appear. 4. Run the example and compare the result with your prediction. 5. Use the practice task before moving on.

Small example

let cache = new Map(); cache.set('lesson', { done: false });

Common mistake

Do not use memory, references, and garbage collection only because it looks advanced. Start from the problem it solves.

Practice task

Change the example, predict the result, then explain the behavior in your own words.

Remember this

Release long-lived references when their data is no longer needed.