JavaScript Conditional statements Examples
1. Using if Statement
The if statement is used to evaluate a particular condition. If the condition holds true, the associated code block is executed.
Syntax:
if ( condition ) {
// If the condition is met,
//code will get executed.
}
Example: In this example, we are using the if statement to find given number is even or odd.
let num = 20;
if (num % 2 === 0) {
console.log("Given number is even number.");
}
if (num % 2 !== 0) {
console.log("Given number is odd number.");
};
Output
Given number is even number.
Explanation: This JavaScript code determines if the variable `num` is even or odd using the modulo operator `%`. If `num` is divisible by 2 without a remainder, it logs “Given number is even number.” Otherwise, it logs “Given number is odd number.”
2. Using if-else Statement
The if-else statement will perform some action for a specific condition. Here we are using the else statement in which the else statement is written after the if statement and it has no condition in their code block.
Syntax:
if (condition1) {
// Executes when condition1 is true
if (condition2) {
// Executes when condition2 is true
}
}
Example: In this example, we are using if-else conditional statement to check the driving licence eligibility date.
let age = 25;
if (age >= 18) {
console.log("You are eligible of driving licence")
} else {
console.log("You are not eligible for driving licence")
};
Output
You are eligible of driving licence
Explanation: This JavaScript code checks if the variable `age` is greater than or equal to 18. If true, it logs “You are eligible for a driving license.” Otherwise, it logs “You are not eligible for a driving license.” This indicates eligibility for driving based on age.
3. else if Statement
The else if statement in JavaScript allows handling multiple possible conditions and outputs, evaluating more than two options based on whether the conditions are true or false.
Syntax:
if (1st condition) {
// Code for 1st condition
} else if (2nd condition) {
// ode for 2nd condition
} else if (3rd condition) {
// Code for 3rd condition
} else {
// ode that will execute if all
// above conditions are false
}
Example: In this example, we are using the above-explained approach.
const num = 0;
if (num > 0) {
console.log("Given number is positive.");
} else if (num < 0) {
console.log("Given number is negative.");
} else {
console.log("Given number is zero.");
};
Output
Given number is zero.
Explanation: This JavaScript code determines whether the constant `num` is positive, negative, or zero. If `num` is greater than 0, it logs “Given number is positive.” If `num` is less than 0, it logs “Given number is negative.” If neither condition is met (i.e., `num` is zero), it logs “Given number is zero.”
4. Using Switch Statement (JavaScript Switch Case)
As the number of conditions increases, you can use multiple else-if statements in JavaScript. but when we dealing with many conditions, the switch statement may be a more preferred option.
Syntax:
switch (expression) {
case value1:
statement1;
break;
case value2:
statement2;
break;
. . .
case valueN:
statementN;
break;
default:
statementDefault;
};
Example: In this example, we find a branch name Based on the student’s marks, this switch statement assigns a specific engineering branch to the variable Branch. The output displays the student’s branch name,
const marks = 85;
let Branch;
switch (true) {
case marks >= 90:
Branch = "Computer science engineering";
break;
case marks >= 80:
Branch = "Mechanical engineering";
break;
case marks >= 70:
Branch = "Chemical engineering";
break;
case marks >= 60:
Branch = "Electronics and communication";
break;
case marks >= 50:
Branch = "Civil engineering";
break;
default:
Branch = "Bio technology";
break;
}
console.log(`Student Branch name is : ${Branch}`);
Output
Student Branch name is : Mechanical engineering
Explanation:
This JavaScript code assigns a branch of engineering to a student based on their marks. It uses a switch statement with cases for different mark ranges. The student’s branch is determined according to their marks and logged to the console.
Conditional Statements in JavaScript
JavaScript conditional statements allow you to execute specific blocks of code based on conditions. If the condition is met, a particular block of code will run; otherwise, another block of code will execute based on the condition.
There are several methods that can be used to perform Conditional Statements in JavaScript.
| Conditional Statement | Description |
|---|---|
| if statement | Executes a block of code if a specified condition is true. |
| else statement | Executes a block of code if the same condition of the preceding if statement is false. |
| else if statement | Adds more conditions to the if statement, allowing for multiple alternative conditions to be tested. |
| switch statement | Evaluates an expression, then executes the case statement that matches the expression’s value. |
| ternary operator | Provides a concise way to write if-else statements in a single line. |
| Nested if else statement | Allows for multiple conditions to be checked in a hierarchical manner. |
This table outlines the key characteristics and use cases of each type of conditional statement. Now let’s understand each conditional statement in detail along with the examples.
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