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JS If Else
if Statement:
The if statement is used to execute a block of code only if a specified condition evaluates to true.
Syntax:
if (condition) {
// Code to execute if condition is true
}
if...else Statement:
The if...else statement allows you to execute one block of code if the condition is true and another block if the condition is false
Syntax:
if (condition) {
// Code to execute if condition is true
} else {
// Code to execute if condition is false
}
Example
let age = 20;
if (age >= 18) {
console.log("You are eligible to vote.");
} else {
console.log("You are not eligible to vote.");
}
if...else if...else Statement
For multiple conditions, you can use else if blocks.
Syntax:
if (condition) {
// Code to execute if condition is true
} else if(condition2) {
// Code to execute else if condition is true
} else {
// Code to execute if and else if condition is false
}
Example
let score = 85;
if (score >= 90) {
console.log("Grade: A");
} else if (score >= 80) {
console.log("Grade: B");
} else if (score >= 70) {
console.log("Grade: C");
} else {
console.log("Grade: F");
}
Ternary Operator:
For simple if...else conditions, you can use the ternary operator:
Example
let age = 20;
let message = age >= 18 ? "You are an adult." : "You are a minor.";
console.log(message);
Nested if...else:
You can nest if...else statements inside each other, but keep readability in mind.
Example
let number = 10;
if (number > 0) {
if (number % 2 === 0) {
console.log("The number is positive and even.");
} else {
console.log("The number is positive and odd.");
}
} else {
console.log("The number is not positive.");
}
Logical Operators in Conditions
You can use logical operators (&&, ||, !) to combine conditions.
1.AND (&&):
Example
let age = 25;
if (age > 18 && age < 30) {
console.log("You are in your 20s.");
}
2.OR (||):
Example
let day = "Saturday";
if (day === "Saturday" || day === "Sunday") {
console.log("It's the weekend!");
}
3.NOT (!):
Example
let isRaining = false;
if (!isRaining) {
console.log("You can go outside without an umbrella.");
}