Summary
This chapter explains how to declare functions in JavaScript, detailing the syntax for defining named functions with parameters and how to structure their bodies. It also covers best practices for clear, descriptive naming using lower camel case.

General domain of usage
Performing arithmetic operations and printing results.

To begin working with functions in JavaScript, you need to understand the syntax for declaring them. A function declaration starts with the `function` keyword, followed by the name you choose for your function. After the name, you use parentheses `()` to enclose any parameters the function might take. The body of the function is enclosed in curly braces `{}`. Inside the curly braces, you write the code that will run whenever the function is called. Here is a step-by-step breakdown:

- Write the `function` keyword to tell JavaScript you are creating a function;
- Choose a descriptive name for your function and write it immediately after the `function` keyword;
- Add parentheses after the name—these can include parameter names if your function will use input values;
- Open a curly brace to start the function body;
- Write the statements you want the function to perform;
- Close the curly brace to end the function body.


function addAndLog(a, b) {
  const sum = a + b;
  console.log("The sum is: " + sum);
}

When naming your functions, always follow clear and consistent naming conventions. Function names should be **descriptive** and use **lower camel case**, which means starting with a lowercase letter and capitalizing the first letter of each subsequent word, like `calculateTotal` or `sendEmail`. 

Avoid starting function names with numbers or special characters, and do not use spaces. Good function names describe what the function does, making your code easier to read and maintain. Stick to **verbs or verb phrases**, since functions usually perform actions.

Which of the following are valid JavaScript function declarations? Select all that apply.

JavaScript functions from the fundamentals to modern syntax and best practices. Gain understanding of how functions shape every part of JavaScript, helping create clean, modular, and efficient code. Master both classic patterns and modern approaches to writing reusable, maintainable functions for any project.

Discover how functions organize code, make it reusable, and simplify complex logic. Explore what functions are, why they're essential, and how to define and call them to build cleaner, more efficient JavaScript programs.

Understand how information flows through functions and how scope defines where variables live and interact. Master parameters, return values, and local variables to write predictable, modular code that behaves as expected.

Explore the expressive side of JavaScript with modern syntax and functional techniques. Use arrow functions, callbacks, and function expressions to write concise, flexible, and reusable code that fits today's JavaScript standards.

Function Declarations

Function Declarations