🧩 Default Parameters in JavaScript

Default parameters allow you to set default values for function parameters. If no value is passed, the default will be used.

✅ Syntax Example

function greet(name = "Guest") {
  console.log(`Hello, ${name}!`);
}

greet();         // Hello, Guest!
greet("Alice");  // Hello, Alice!

📌 Behind the Scenes

Before ES6, developers used the OR operator (`||`) to simulate default values:

function greet(name) {
  name = name || "Guest";
  console.log("Hello, " + name);
}

🎯 Use Cases

• Optional function arguments
• Better readability and fewer conditional checks
• Useful in utility/helper functions

⚠️ Watch Out!

Default parameters only apply if the argument is undefined, not null.

function demo(value = "default") {
  console.log(value);
}

demo(undefined); // "default"
demo(null);      // null