JavaScript Flow Conditionals

📘 JavaScript Flow Conditionals (if, else, switch)

1️⃣ if Statement

The if statement executes a block of code only if a specified condition is true.

let age = 20;

if (age >= 18) {
  console.log("You are an adult.");
}
// Output: You are an adult.
  

2️⃣ if...else Statement

The if...else statement provides an alternative block of code if the condition is false.

let score = 40;

if (score >= 50) {
  console.log("You passed.");
} else {
  console.log("You failed.");
}
// Output: You failed.
  

3️⃣ if...else if...else Statement

Use else if when you want to test multiple conditions.

let temp = 25;

if (temp > 30) {
  console.log("It's hot.");
} else if (temp >= 20) {
  console.log("It's warm.");
} else {
  console.log("It's cold.");
}
// Output: It's warm.
  

4️⃣ switch Statement

The switch statement evaluates an expression and executes code based on matching cases. It’s often cleaner than writing many else if statements.

let day = "Monday";

switch (day) {
  case "Monday":
    console.log("Start of the week.");
    break;
  case "Friday":
    console.log("End of the workweek.");
    break;
  default:
    console.log("It's a regular day.");
}
// Output: Start of the week.
  

✅ Quick Recap

• if → Runs code if condition is true.
• if...else → Runs one block if true, another if false.
• if...else if...else → Multiple conditions.
• switch → Cleaner way to handle many possible values of the same variable.
• Always use break in switch cases to prevent fall-through unless intentional.

📌 Mini Project: Grade Checker

let marks = 85;

if (marks >= 90) {
  console.log("Grade: A");
} else if (marks >= 75) {
  console.log("Grade: B");
} else if (marks >= 50) {
  console.log("Grade: C");
} else {
  console.log("Grade: F");
}
// Output: Grade: B