Lesson 9 of 3327%

(Progress persistence is disabled until Phase 9)

JavaScript
Intermediate
20 min

Functions

Create reusable blocks of code.

Learning Objectives

  • Declaring a function

Functions

Welcome to this lesson on Functions. JavaScript is the programming language of the web, and functions is a fundamental piece of that ecosystem.

Explanation

When your browser loads a web page, the HTML creates the structure, the CSS creates the style, and JavaScript creates the interactivity. JavaScript can update both HTML and CSS in real-time.

Code Examples

Here is a simple snippet demonstrating this concept:

  return a * b;
}
multiply(5, 4);\n```

### Explanation of Code

In the example above, we define the logic required to implement the concept, and then execute it. The JavaScript engine parses this syntax and runs it.

<Callout type="warning">
**Common Mistake:** Watch out for syntax errors! Missing a bracket or a semicolon can sometimes break your entire script.
</Callout>

### Try It Yourself

Put this into practice! The BrowserCode runtime allows you to execute JavaScript securely in your browser.

<TryItButton />

### Key Takeaways
- JavaScript makes pages interactive.
- Always check your browser console for errors.

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