JavaScript If...Else Statements

[welcomewiki]

Conditional statements in JavaScript 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:

• if statement - use this statement if you want to execute some code only if a specified condition is true
• if...else statement - use this statement if you want to execute some code if the condition is true and another code if the condition is false
• if...else if....else statement - use this statement if you want to select one of many blocks of code to be executed
• switch statement - use this statement if you want to select one of many blocks of code to be executed

If Statement

You should use the if statement if you want to execute some code only if a specified condition is true.
Syntax

if (condition)
{
code to be executed if condition is true
} Note that if is written in lowercase letters. Using uppercase letters (IF) will generate a JavaScript error!




Example



Notice that there is no ..else.. in this syntax. You tell the browser to execute some code only if the specified condition is true.


If...else Statement

If you want to execute some code if a condition is true and another code if the condition is not true, use the if....else statement.
Syntax

if (condition)
{
code to be executed if condition is true
}
else
{
code to be executed if condition is not true
}

Example







If...else if...else Statement

You should use the if....else if...else statement if you want to select one of many sets of lines to execute.
Syntax

if (condition1)
{
code to be executed if condition1 is true
}
else if (condition2)
{
code to be executed if condition2 is true
}
else
{
code to be executed if condition1 and condition2 are not true
}
Example

Similar Threads:

• JavaScript Statements
• JavaScript Where To
• JavaScript How To
• JavaScript Introduction
• JavaScript Tutorial

[welcomewiki]

Random link
This example demonstrates a link, when you click on the link it will take you to W3Schools.com OR to RefsnesData.no. There is a 50% chance for each of them.