JavaScript If Else

The if...else statement is used to perform different actions based on different conditions. It allows you to test if a condition is true or false and execute code accordingly.

 

1. Basic Syntax of If Else:

if (condition) {
    // Code to execute if condition is true
} else {
    // Code to execute if condition is false
}

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Example:

let x = 10;
if (x > 5) {
    console.log("x is greater than 5");
} else {
    console.log("x is not greater than 5");
}

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Explanation:

  • The condition x > 5 is true, so the message "x is greater than 5" will be logged.

2. Else If:

You can add multiple conditions using else if to check for different possibilities.

Syntax of If Else If:

if (condition1) {
    // Code to execute if condition1 is true
} else if (condition2) {
    // Code to execute if condition2 is true
} else {
    // Code to execute if all conditions are false
}

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Example:

let age = 18;
if (age < 18) {
    console.log("You are a minor");
} else if (age >= 18 && age <= 65) {
    console.log("You are an adult");
} else {
    console.log("You are a senior");
}

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Explanation:

  • If the age is less than 18, the message "You are a minor" is printed.
  • If the age is between 18 and 65, the message "You are an adult" is printed.
  • If the age is greater than 65, the message "You are a senior" is printed.

3. Nested If Else:

You can also nest if...else statements within each other to check for multiple conditions.

Example:

let x = 10;
let y = 20;

if (x > y) {
    console.log("x is greater than y");
} else {
    if (x < y) {
        console.log("x is less than y");
    } else {
        console.log("x is equal to y");
    }
}

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Explanation:

  • First, it checks if x > y. If false, it checks if x < y. If false, it concludes that x is equal to y.

 

4. Ternary Operator (Shortcut for If Else):

The ternary operator provides a more concise way of writing if...else statements. It’s used for simple conditions.

Syntax:

condition ? expressionIfTrue : expressionIfFalse;

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Example:

let age = 18;
let result = age >= 18 ? "Adult" : "Minor";
console.log(result); // "Adult"

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Explanation:

  • If the condition age >= 18 is true, "Adult" is assigned to result, otherwise "Minor" is assigned.

Conclusion:

  • if...else allows you to control the flow of code based on conditions.
  • else if helps you handle multiple conditions.
  • Nested if...else enables deeper decision-making logic.
  • The ternary operator provides a shorter form for simple conditions.