Comparing if-else, switch-case, and Object Lookup in JavaScript

When writing conditional logic in JavaScript, developers have multiple choices, including if-else, switch-case, and object lookup. Each method has its advantages and disadvantages depending on readability, maintainability, and performance. This article compares these three approaches to determine which is best for different scenarios.

1. if-else

The if-else statement is the most commonly used conditional structure in JavaScript. It executes code blocks based on whether a condition evaluates to true or false.

Example

function getUserAccessLevel(role) {
  if (role === 'admin') {
    return 'Full Access';
  } else if (role === 'editor') {
    return 'Edit Access';
  } else {
    return 'Read-Only Access';
  }
}
console.log(getUserAccessLevel('admin')); // Full Access

Pros

• Simple and easy to understand.
• Works well with multiple conditions.
• Supports complex conditions involving logical operators.

Cons

• Becomes less readable with too many conditions.
• Performance can degrade if many conditions need to be checked sequentially.

2. switch-case

The switch-case statement is useful when dealing with multiple discrete values. It improves readability by reducing repetitive if-else statements.

Example

function getHttpStatusMessage(statusCode) {
  switch (statusCode) {
    case 200:
      return 'OK';
    case 400:
      return 'Bad Request';
    case 404:
      return 'Not Found';
    case 500:
      return 'Internal Server Error';
    default:
      return 'Unknown Status';
  }
}
console.log(getHttpStatusMessage(404)); // Not Found

Pros

• More readable than multiple if-else blocks when dealing with fixed values.
• Can be more performant when compiled into jump tables in certain engines.

Cons

• Only works well with discrete values (e.g., strings, numbers).
• Requires explicit break statements to avoid fall-through behavior.
• Less flexible than if-else when dealing with complex conditions.

3. object lookup

Object lookup is an alternative to if-else and switch-case, offering a cleaner and more performant way to map inputs to outputs.

Example

const paymentFees = {
  credit_card: 2.5,
  paypal: 3.0,
  bank_transfer: 1.0,
};

function getPaymentFee(method) {
  return paymentFees[method] || 0;
}
console.log(getPaymentFee('paypal')); // 3.0

Pros

• More readable and concise than if-else and switch-case.
• Faster lookup performance, as accessing an object property is generally fast.
• Easily extendable without modifying control structures.

Cons

• Not suitable for complex conditions or computations.
• Requires prior knowledge of the keys.

Conclusion: Which One Is Best?

Criteria	if-else	switch-case	Object Lookup
Readability	Good (few conditions)	Good (discrete values)	Best (simple mappings)
Maintainability	Poor (many conditions)	Moderate	Best (scalable)
Performance	Moderate	Good	Best lookup
Complexity Handling	Best	Limited	Poor (only key-value)

• Use if-else when dealing with complex conditions or logical expressions.
• Use switch-case when checking discrete values and needing better readability.
• Use object lookup for key-value lookups to improve performance and maintainability.

Choosing the best approach depends on the specific use case, but object lookup is often the most efficient for simple value mappings.