Why Do We Use If/Else Statements in JavaScript? A Beginner-Friendly Guide

JavaScript is a pivotal programming language for web development. It enables dynamic interactions and logic, much like most other programming languages. One of the key ways to control the flow of a program is through conditionals. Among the various conditional statements in JavaScript, the if/else statement is one of the most commonly used. In the next few lines, we’ll explore why do we use if/else statements in JavaScript and how they differ from other types of conditionals.

How to Use If Else Statement in JavaScript

In JavaScript, if...else statements allow you to control the logic and flow of your program by executing different blocks of code based on a given condition. In essence, they enable programs to make smart decisions—just like we do as human beings when faced with different situations.

Here’s a code snippet showing the basic structure of if...else statements in JavaScript:

if (condition) {
  // code runs if condition is true
} else {
  // code runs if condition is false
}

Yet, we can chain multiple conditions with else if:

if (condition1) {
  // code runs if condition1 is true
} if else(condition2) {
  // code runs if condition2 is false
} if else(condition3) {
  // code runs if condition3 is false
} else {
  // code runs if all conditions are false
}

Why Do We Use If/Else Statements in JavaScript?

We use them for different reasons,

1. Control Flow

They can help in controlling what happen next in a program depending on whether a condition is true or false.

if (isRaining) {
  takeAnUmbrella();
} else {
  wearSunglasses();
}

2. Validation

In real-world scenarios, if/else statements in JavaScript are often used for data validation—a crucial component of any web application.

if (password.length < 6) {
  alert("Password too short!");
} else {
  alert("Password accepted.");
}

3. Avoid Unnecessary Code Execution

Using if/else statements in JavaScript allows you to skip over parts of the code that aren’t necessary for a given situation, which helps save processing power, memory, and execution time.

let isUserPremium = false;

if (isUserPremium) {
  loadPremiumFeatures(); // heavy function, lots of data
} else {
  loadBasicFeatures(); // lighter
}

This way, we avoid loading expensive resources (like big files or special features) for users who don’t need them.

When to Use If/Else Statements vs Other Conditionals in JavaScript

Using if/else statements in JavaScript is especially suitable when the logic is complex or involves multiple comparisons. It’s also a wise choice when aiming to improve the readability of your program.

Here’s a table summarising when each type of conditional statement is best suited, compared to if/else:

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If/Else Statements Best Practices in JavaScript

I believe it’s crucial to follow best practices when using if/else statements in JavaScript to write cleaner, more readable, and maintainable code. Here are some of the top guidelines you can follow:

1. Keep Condition Simple and Readable

• Use clear and concise condition expressions.
• Extract conditions into clearly named constants or functions to improve readability.
• Avoid long, complex boolean logic in one line.

Avoid:

if ((user.age > 18 && user.verified) || user.admin && !user.banned) { ... }

Better:

const isAdultUser = user.age > 18 && user.verified;
const isTrustedAdmin = user.admin && !user.banned;

if (isAdultUser || isTrustedAdmin) { ... }

2. Avoid Deep Nesting

• Refactor deeply nested if/else blocks into guard clauses or separate functions.

Avoid:

if (user) {
  if (user.active) {
    if (!user.banned) {
      // do something
    }
  }
}

Better (guard clauses):

if (!user || !user.active || user.banned) return;

// do something

3. Use Strict Equality (===)

• Always prefer === over == to avoid unexpected type coercion.

Avoid:

if (user.role == '1') { ... } // '1' or 1, both will return true

Better:

if (user.role === '1') { ... } 

4. Return Early to Reduce Else Blocks

• Sometimes instead of using else, use early return to keep code flatter and more readable.

Avoid:

if (!user) {
  console.log('No user found');
} else {
  processUser(user);
}

Better:

if (!user) {
  console.log('No user found');
  return;
}
processUser(user);

5. Use default or else to Handle Unexpected Cases

• In other case, you would need to include a fallback (else) or default in case no condition is met.

Avoid:

if (role === 'admin') {
  // ...
} else if (role === 'editor') {
  // ...
}

Better:

if (role === 'admin') {
  // ...
} else if (role === 'editor') {
  // ...
} else {
  // Handle unknown role
}

Conclusion

If/else statements in JavaScript are a vital element in controlling the flow of programs execution. they can be used in various case scenarios from handling complex logic to validating user-input data. it’s important for JavaScript developers to understand how to use if/else statements effectively. Writing clean, well-structured conditional logic not only improves code readability and maintainability but also reduces bugs and makes the application easier to scale and debug. Mastering if/else statements in JavaScript is one of the first steps toward becoming a proficient JavaScript developer.