When coding in JavaScript, you'll often encounter situations where you need to handle default values or fallbacks. Two common methods for this are using Nullish Coalescing (??) and Logical OR (||) operators. Let's dive into when to use each to make your code cleaner and more efficient.
Nullish Coalescing (??) is a relatively new addition to JavaScript, added in ES2020. It's specifically designed to handle cases where you want to use a fallback value only if a variable is null or undefined. For example, if you have a variable `value` that might be null or undefined, using `value ?? 'default'` will assign 'default' to the variable only if `value` is null or undefined.
On the other hand, the Logical OR (||) operator is more broadly used for providing a default value when the variable is falsy, which includes null, undefined, empty string, 0, NaN, and false. This means that using `value || 'default'` will assign 'default' to the variable if `value` is any falsy value.
So, when should you choose Nullish Coalescing over Logical OR?
Use Nullish Coalescing (??) when you want to specifically check for null or undefined values and ignore other falsy values. This is particularly useful when working with objects or variables that may have legitimate falsy values other than null or undefined that you want to retain.
For example, consider a scenario where you have a variable that could be an empty string, but you want to assign a default value only if the variable is explicitly null or undefined. Using Nullish Coalescing like `variable ?? 'default'` ensures that 'default' is assigned only if `variable` is null or undefined, not when it's an empty string.
On the other hand, if you're working with variables that could have various falsy values that you want to handle uniformly, Logical OR (||) might be more suitable. It provides a more inclusive check for any falsy value, making it a broader choice for setting default values.
In summary, Nullish Coalescing (??) offers a precise way to handle null or undefined values without affecting other falsy values, while Logical OR (||) provides a more general approach to handling any falsy value.
By understanding the differences between Nullish Coalescing and Logical OR operators, you can make better-informed decisions on when to use each in your code. Choose the method that aligns with your specific requirements to write cleaner, more efficient code that handles default values effectively.