How do the Elvis and Safe Navigation Operators Protect JavaScript Values?

Safeguarding JavaScript Values: Elvis and Safe Navigation Operators

In JavaScript, ensuring that variables are not null or undefined is crucial to prevent errors. The Elvis operator and safe navigation operator are two techniques that can help with this task.

Elvis Operator: A Conditional Shortcut

Similar to Java's ternary operator, the Elvis operator (?:) assigns a default value if the left-hand expression resolves to false, null, or undefined. For instance:

const displayName = user.name ?: "Anonymous";

If user.name exists and is not empty, displayName will receive its value. Otherwise, it will default to "Anonymous."

Safe Navigation Operator: Avoiding NullPointerExceptions

The safe navigation operator (?.) prevents NullPointerExceptions when accessing properties of potentially null objects. Instead of throwing an exception, it simply returns null. For example:

const streetName = user?.address?.street;

If user or user.address is null, streetName will remain null. This protects against errors when accessing properties of non-existent objects.

Alternatives in JavaScript

Currently, JavaScript lacks an Elvis operator. Instead, you can use the logical OR operator (||) for conditional assignments:

const displayName = user.name || "Anonymous";

However, there's no direct equivalent for the safe navigation operator. For a similar functionality, consider using CoffeeScript, which provides an existential operator:

const zip = lottery.drawWinner?().address?.zipcode;

CoffeeScript also offers other syntactic enhancements like multiline comments, function shortcuts, and "sexy" function calling. These features can improve readability and expressiveness in JavaScript code.

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