If else statement in javascript

Conditional statements are used to perform different actions based on different conditions.

Conditional Statements

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
• Use switch to specify many alternative blocks of code to be executed

The switch statement is described in the next chapter.

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
}

Note that if is in lowercase letters. Uppercase letters [If or IF] will generate a JavaScript error.

Example

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

if [hour < 18] {
  greeting = "Good day";
}

The result of greeting will be:

Try it Yourself »

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 result of greeting will be:

Try it Yourself »

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:

Try it Yourself »

More Examples

Random link
This example will write a link to either W3Schools or to the World Wildlife Foundation [WWF]. By using a random number, there is a 50% chance for each of the links.

Example

If the hour is less than 20, output "Good day":

let hour = new Date[].getHours[];
if [hour < 20] {
  document.getElementById["demo"].innerHTML = "Good day";
}

Try it Yourself »

Output "Good day" or "Good evening":

let hour = new Date[].getHours[];
if [hour < 20] {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

Try it Yourself »

More examples below.

Definition and Usage

The if/else statement executes a block of code if a specified condition is true. If the condition is false, another block of code can be executed.

The if/else statement is a part of JavaScript's "Conditional" Statements, which are used to perform different actions based on different conditions.

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
• Use switch to select one of many blocks of code to be executed

Syntax

The if statement specifies a block of code to be executed if a condition is true:

if [condition] {
  // block of code to be executed if the condition is true
}

The else statement specifies 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
}

The else if statement specifies a new condition if the first condition is false:

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
}

Parameter Values

More Examples

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":

var time = new Date[].getHours[];
if [time < 10] {
  greeting = "Good morning";
} else if [time < 20] {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

Try it Yourself »

If the first