JavaScript if-else

JavaScript conditional statements allow programs to make decisions based on specific conditions. They control the flow of execution, enabling different actions for different scenarios.

JavaScript if-statement

It is a conditional statement that determines whether a specific action or block of code will run based on a condition. If the condition is true, the code executes; if false, it does not.

Syntax

if (condition) {
 // Code to be executed if the condition is true
}

Now let's understand this with the help of an example:

// JavaScript program to illustrate If statement let age = 19; if (age > 18) console.log("Congratulations, You are eligible to drive"); 

Congratulations, You are eligible to drive 

JavaScript 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. It's a way to handle two possible outcomes based on a condition.

Syntax

if (condition)
{
 // Executes this block if
 // condition is true
}
else
{
 // Executes this block if
 // condition is false
}

Now let's understand this with the help of example

// JavaScript program to illustrate If-else statement let i = 10; if (i < 15)  console.log("i is less than 15"); else  console.log("I am Not in if"); 

i is less than 15 

JavaScript nested-if statement

JavaScript lets you put an if statement inside another if statement. This is called a nested if, where one if or else is inside another.

Syntax

if (condition1) 
{
 // Executes when condition1 is true
 if (condition2) 
 {
 // Executes when condition2 is true
 }
}

Now let's understand this with the help of example

// JavaScript program to illustrate nested-if statement let i = 10; if (i == 10) { // First if statement  if (i < 15) {  console.log("i is smaller than 15");  // Nested - if statement  // Will only be executed if statement above  // it is true  if (i < 12)  console.log("i is smaller than 12 too");  else  console.log("i is greater than 15");  } } 

i is smaller than 15 i is smaller than 12 too 

JavaScript if-else-if statement

The if-else-if ladder is used to check multiple conditions in sequence. Once a true condition is found, its block executes, and the rest are skipped.

Syntax

if (condition)
 statement;
else if (condition)
 statement;
.
.
else
 statement;

Now let's understand this with the help of example

// JavaScript program to illustrate nested-if statement let i = 20; if (i == 10)  console.log("i is 10"); else if (i == 15)  console.log("i is 15"); else if (i == 20)  console.log("i is 20"); else  console.log("i is not present"); 

i is 20