5Conditional Statements in JavaScript

What Are Conditional Statements?

Conditional statements let your code make decisions. They check whether something is true or false and then decide what to do next — kind of like a mini decision tree in your program.

let temperature = 30;

if (temperature > 25) {
  console.log("It's hot outside!");
}

Here, the `if` block runs only if the condition inside the parentheses is true.

If, Else If, and Else

When you have multiple possibilities, you can chain conditions using `else if` and finish with a fallback `else` block.

let score = 82;

if (score >= 90) {
  console.log("Excellent!");
} else if (score >= 70) {
  console.log("Good job!");
} else {
  console.log("Keep practicing!");
}

JavaScript will run the first condition that’s true and skip the rest.

Comparison and Logical Operators Together

You can combine comparisons using logical operators like `&&` (AND) and `||` (OR) for more complex checks.

let age = 22;
let hasLicense = true;

if (age >= 18 && hasLicense) {
  console.log("You can drive.");
} else {
  console.log("You can’t drive yet.");
}

The Switch Statement

When you need to compare the same variable against multiple values, a `switch` statement can make your code cleaner than writing lots of `else if` lines.

let day = "Tuesday";

switch (day) {
  case "Monday":
    console.log("Start of the week!");
    break;
  case "Friday":
    console.log("Almost weekend!");
    break;
  case "Saturday":
  case "Sunday":
    console.log("Weekend vibes!");
    break;
  default:
    console.log("Just another day.");
}

Each `case` is checked in order, and the `break` statement stops JavaScript from checking the next one. If no case matches, the `default` block runs.

Ternary Operator

The ternary operator is a shorthand for simple `if...else` conditions. It uses the syntax: `condition ? valueIfTrue : valueIfFalse`.

let isMember = true;
let message = isMember ? "Welcome back!" : "Please sign up.";
console.log(message);

Nested Conditionals

You can also place one conditional inside another. Just be careful not to make them too complicated or deeply nested — readability matters.

let time = 14;
let isWeekend = false;

if (time < 12) {
  console.log("Good morning!");
} else {
  if (isWeekend) {
    console.log("Enjoy your afternoon off!");
  } else {
    console.log("Back to work!");
  }
}

Mini Challenge

Write a program that checks a variable `score` and prints: - "Excellent" if it’s 90 or above, - "Good" if it’s between 70 and 89, - "Needs Improvement" otherwise.

// Example:
let score = 68;

if (score >= 90) {
  console.log("Excellent");
} else if (score >= 70) {
  console.log("Good");
} else {
  console.log("Needs Improvement");
}

Key Takeaway

Conditionals bring logic and decision-making to your code. With `if`, `else`, and `switch`, your programs can respond dynamically to different inputs and situations.

MDN Docs: if...else and switch Statements