JavaScript if else Statement

While writing a program, there may be a situation when you need to adopt one out of a given set of paths. In such cases, you need to use conditional statements that allow your program to make correct decisions and perform the right actions.

JavaScript supports conditional statements which are used to perform different actions based on different conditions. Here we will explain the if..else statement.

Very often when you write code, you want to perform different actions for different decisions.

You can use conditional statements in your code to do this.

In JavaScript we have the following conditional statements:

  • Use if to specify a block of code to be executed, if a specified condition is true
  • Use else to specify a block of code to be executed, if the same condition is false
  • Use else if to specify a new condition to test, if the first condition is false

The if Statement

Use the if statement to specify a block of JavaScript code to be executed if a condition is true.

Syntax

if (condition) {
  //  block of code to be executed if the condition is true
}

Example

Make a "Good day" greeting if the hour is less than 18:00:

if (hour < 18) {
  greeting = "Good day";
}

 

The else Statement

Use the else statement to specify a block of code to be executed if the condition is false.

if (condition) {
  //  block of code to be executed if the condition is true
} else { 
  //  block of code to be executed if the condition is false
}

Example

If the hour is less than 18, create a "Good day" greeting, otherwise "Good evening":

if (hour < 18) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

 

The else if Statement

Use the else if statement to specify a new condition if the first condition is false.

Syntax

if (condition1) {
  //  block of code to be executed if condition1 is true
} else if (condition2) {
  //  block of code to be executed if the condition1 is false and condition2 is true
} else {
  //  block of code to be executed if the condition1 is false and condition2 is false
}

Example

If time is less than 10:00, create a "Good morning" greeting, if not, but time is less than 20:00, create a "Good day" greeting, otherwise a "Good evening":

if (time < 10) {
  greeting = "Good morning";
} else if (time < 20) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

The result of greeting will be:

Good evening