Arrow functions and callbacks

What this means

Arrow functions are a shorter way to write JavaScript functions. In React, you see them in event handlers, array map, filters, and quick callbacks.

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

React code often passes functions around instead of running code immediately. When you understand arrow functions, event handlers like onClick={() => setOpen(true)} become much less confusing.

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

const handleClick = () => {
  console.log("Clicked");
};

Common mistake

Do not call a function immediately when React expects a callback. onClick={save()} runs now; onClick={() => save()} runs after the click.

Practice task

Write a button handler as an arrow function, then use it in onClick.

Remember this

Callbacks are functions saved for later.