JavaScript If-Else Statements

In JavaScript if-else statements are also known as conditional statements. If-else statements are used to execute any block of code conditionally e.g. if you want to execute any code only if condition satisfies that the input entered by the user is less than 5. At this point you can use if condition.

There are 3 types of if conditions:

1. if statement

2. if-else statement

3. if-else…if-else statement

1. if statement:

If you have a code that you want to execute only when the condition in if statement is true and there is no other code to be executed if the condition is false.

2. if-else statement:

If you have 2 pieces of code from which first part of the code will be executed when if condition is true and the other one will be executed when if condition is false.

3. if…else-if…else statements:

If you have number of conditions and for every condition you have another trapping if condition satisfying if condition, if…else-if…else statements can be used.

Example: if statement

var x=10;
var y=20;
   
if(x<y)
{
    alert('y is greater than x.');
}

Example: if-else statement

var x=10;
var y=5;
   
if(x<y)
{
    alert('y is greater than x.');
}
else
{
    alert('x is greater than y.');
}

Example: if...else-if...else statements

var x=10;
var y=10;
    
if(x<y)
{
    alert('y is greater than x.');
}
else if(x>y)
{
    alert('x is greater than y.');
}
else
{
    alert('x=y');
}

If you have number of conditions then there is other option in JavaScript for conditional code execution.

Continue to next tutorial: JavaScript Switch Case statement to learn how to use variable based javascript switch conditional ladder.