In this tutorial, you will learn about JavaScript if else statement, syntax, and create a decision-making program with the help of examples.
In the previous JavaScript tutorial, we have seen all about JavaScript for loops to execute a block of code a number of times.
In computer programming, There are many situations array where we have to execute a block of code on the basic of different-2 conditions. In such situations, you can use JavaScript if else statement that can make decisions.
In JavaScript, we have following conditional statements.
- if statement
- if…else statement
- if..else if…else statement
Headings of Contents
JavaScript if statement
JavaScript if statement is used to execute a block of code when the specified condition is true.
Syntax
if ( condition )
{
// block of code to be executed.
};
Explanation:
The if statement evaluate the condition specified inside parenthesis ().
- If the condition evaluates is evaluated true, the code inside the body of if is executed.
- If the condition evaluates false, the code inside the body of if is skipped.
Flowchart of JavaScript if statement

Example: Check a number is greater than 0 or not.
// check a number if greater than 10
num = 20;
if ( num > 10 )
{
console.log(`${num} is greater than 10`);
}
Output will be:- 20 is greater than 10
JavaScript if else statement
JavaScript if statement has an optional clause else, that s used to execute a block of code when the condition is false.
Syntax
if ( condition )
{
// block of code to be executed.
}
else
{
// block of code to be executed
};
Explanation:
The if statement evaluate the condition specified inside parenthesis ().
- If the condition evaluates true, the code inside the body of if is executed.
- If the condition evaluates false, the code inside the body of else is executed.
Flowchart of JavaScript if..else statement

Example: Check the age of the voter.
// Check a voter can vote or not by their age.
age = prompt("Enter your exact age here:- ");
if ( age > 18 )
{
console("You are eligible to vote");
}
else
{
console.log("You are not eligible to vote");
};
Output 1:-
Enter your exact age here:- 20
You are eligible to vote
Output 2:
Enter your exact age here:- 15
You are not eligible to vote
JavaScript if..else if statement
JavaScript if..else if statement is used to execute a block of code when the previous condition is false.
Syntax
if ( condition 1 )
{
// block code 1
}
else if ( condition 2 )
{
// block code 2
else
{
// block code 3
};
Explanation:
- If condition 1 is evaluated true, block code 1 is executed.
- If condition 1 is evaluated false, condition 2 is evaluated.
- If condition 2 is evaluated true, code block 2 is executed.
- If condition 2 is evaluated false, code block 3 is executed.
Flowchart of JavaScript if..else if statement

Example: Check a entered number is positive, negative or not.
number = prompt("Enter any number:- ")
if ( number > 0 )
{
console("The Number is positive.");
}
else if ( number == 0 )
{
console.log("The Number is zero.");
}
else
{
console.log("The Number is negative.");
};
Output 1:
Enter any number:- 10
The Number is positive.
Output 2:
Enter any number:- 0
The Number is zero.
Output 3:
Enter any number:- -10
The Number is negative.
Nested if..else statement
You can also use if..else statement inside another if..else statement, This is known as nested if..else statement.
Example:- Check a entered number is positive, negative or zero.
number = prompt("Enter any number:- ")
if ( number >= 0 )
{
if ( number == 0 )
{
console("Number is zero");
}
else
{
console("Number is positive..");
}
}
else
{
console.log("Number is negative");
};
Conclusion
In this tutorial, you have learned all about JavaScript if-else statements and different types of conditional statements with the help of examples. Conditional statements are very useful to execute a different-2 block of code on the basis of different-2 conditions.
Here we have seen simple examples but when you will work with real life poject, then you will perfomr more complex operations using decision making.
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