JavaScript Conditionals

Conditional Statements

Conditional Statements allow us to perform different actions for different conditions.

Conditional statements run different code depending on true or false conditions.

Conditional statements include:

• if
• if...else
• if...else if...else
• switch
• ternary (? :)

When to use Conditionals

• Use if to specify a code block to be executed, if a specified condition is true
• Use else to specify a code block 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 code blocks to be executed
• Use (? :) (ternary) as a shorthand for if...else

The if Statement

Use if to specify a code block to be executed, if a specified condition is true.

Syntax

if (condition) {

  // code to execute if the condition is true

 }

The else Statement

Use else to specify a code block to be executed, if the same condition is false.

Syntax

if (condition) {

  // code to execute if the condition is true

 }
else {

  // code to execute if the condition is false

 }

The else if Statement

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

Syntax

if (condition1) {

  // code to execute if condition1 is true

 }
else if (condition2) {

  // code to execute if the condition1 is false and condition2 is true

} else {

  // code to execute if the condition1 is false and condition2 is false

 }

The switch Statement

Use switch to specify many alternative code blocks to be executed.

Syntax

switch(expression) {

  case x:

     // code block

        break;

  case y:

     // code block

     break;

  default:

      // code block

 }

Ternary Operator (? :)

Use (? :) (ternary) as a shorthand for if...else.

Example

condition ? expression1 : expression2