JavaScript Logical Operators: The ?? Nullish Coalescing Operator vs || Logical OR Operator

Introduction

JavaScript offers several operators to manage conditional logic and data fallback. Among them, the ?? (nullish coalescing) operator and || (logical OR) operator are commonly used for handling default values. In this blog post, we will delve into these operators, exploring their differences and use cases, accompanied by code snippets for clarity.

Using the Nullish Coalescing (??) Operator

const defaultValue = 'Default Value';
const userInput = null;

const result = userInput ?? defaultValue;

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

Using the Logical OR (||) Operator

const defaultValue = 'Default Value';
const userInput = null;

const result = userInput || defaultValue;

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

Avoiding Pitfalls with the Nullish Coalescing Operator

const fallbackValue = 0;
const userInput = '';

const result = userInput ?? fallbackValue;

console.log(result); // Output: ''

Avoiding Pitfalls with the Logical OR Operator

const fallbackValue = 0;
const userInput = '';

const result = userInput || fallbackValue;

console.log(result); // Output: 0

Conclusion

In JavaScript, the choice between the ?? and || operators depends on your specific requirements. The ?? operator is excellent for dealing with null or undefined values, ensuring that only truly missing values are replaced with defaults. On the other hand, the || operator is versatile and useful in cases where falsy values (e.g., empty strings, zeros) should be replaced.

Understanding the nuances and use cases of these operators empowers you to write cleaner, more reliable code, enhancing the overall quality of your JavaScript applications.