How do you use the conditional OR (||) operator to assign a default value to a variable in JavaScript?

Certainly! In JavaScript, you can use the conditional OR (`||`) operator to assign a default value to a variable if the original value is falsy (e.g., `null`, `undefined`, `false`, `0`, `NaN`, or an empty string).

Here's an example:

// Example 1: Using || to assign a default value

let someVariable = null;

let defaultValue = "Default Value";

// If someVariable is falsy, assign defaultValue; otherwise, keep someVariable

let result = someVariable || defaultValue;

console.log(result);  // Output: Default Value

In this example, `someVariable` is `null`, which is a falsy value. Therefore, the `||` operator assigns the default value (`defaultValue`) to the variable `result`.

You can also use this technique with function parameters to provide default values:

// Example 2: Using || to provide default values for function parameters

function greet(name) {

  // If name is falsy, assign a default value; otherwise, use the provided name

  name = name || "Guest";

  console.log("Hello, " + name + "!");

}

greet();             // Output: Hello, Guest!

greet("John");       // Output: Hello, John!

In this case, if no `name` is provided or if it's a falsy value, the `||` operator assigns the default value `"Guest"` to the `name` variable.

Keep in mind that using the `||` operator for default values has a limitation: if the original value can be a valid falsy value (e.g., `0` or an empty string) and you still want to provide a default in those cases, you may need to use a more complex conditional expression or the nullish coalescing operator (`??`), introduced in ECMAScript 2020. The nullish coalescing operator specifically checks for `null` or `undefined` values:

let someVariable = 0;

let defaultValue = "Default Value";

// If someVariable is null or undefined, assign defaultValue; otherwise, keep someVariable

let result = someVariable ?? defaultValue;

console.log(result);  // Output: 0

In this example, the result is `0` because the nullish coalescing operator doesn't treat `0` as a nullish value.