JavaScript logical OR operator (||) and the nullish coalescing operator (??)

The two JavaScript snippets you provided illustrate the difference between the logical OR operator (||) and the nullish coalescing operator (??). Let's break down how each of these works and the implications of their usage.

Code Snippets

### Using Logical OR (||)

javascript const user = { name: 'John' }; const name = user.name || 'Guest';

Using Nullish Coalescing (??)

javascript const user = { name: 'John' }; const name = user.name ?? 'Guest';

Differences Explained

1. Behavior with Falsy Values

- **Logical OR (||): This operator returns the right-hand operand if the left-hand operand is falsy. Falsy values in JavaScript include false, 0, "" (empty string), null, undefined, and NaN. Therefore, if user.name is any of these falsy values, name will be assigned 'Guest'.

Example: javascript ~js const user = { name: '' }; // Empty string is falsy const name = user.name || 'Guest'; // name will be 'Guest' ~

• **Nullish Coalescing (??): This operator only considers null and undefined as "nullish" values. It will return the right-hand operand only if the left-hand operand is null or undefined. Any other value, including falsy values like 0 or "", will be returned as is.

  Example: javascript ~js const user = { name: '' }; // Empty string is not nullish const name = user.name ?? 'Guest'; // name will be '' (empty string) ~

2. Use Cases

- **Use || when: You want to provide a default value for any falsy value. This is useful in scenarios where any falsy input should trigger a fallback.

• Use ?? when: You want to provide a default value only for null or undefined. This is particularly useful when you want to allow other falsy values (like 0 or "") to be valid.

Summary

In summary, the key difference between the two snippets lies in how they handle different types of values:

- || will default to 'Guest' for any falsy value.

• ?? will only default to 'Guest' for null or undefined.

Understanding these differences can help you choose the appropriate operator based on your specific needs in JavaScript programming.