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JavaScript•JavaScript Foundations

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

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