w3resource

JavaScript: Switch statement

Description

The switch statement allows to make a decision from the number of choices.

If a match is found to a case label, the program executes the associated statement.

If no match is found with any of the case statements, only the statements following the default are executed. 

If no default statement is found, the program continues execution at the statement following the end of the switch.

Note that switch statement is almost similar to a series of if statements on the same expression.

Syntax

switch (expression){
  case label : 
    statements; 
    break;
  case label :
    statements;
    break;
 ...    default : statements;
}

Parameters

expression: Value matched against the label.

label: An Identifier to be matched against expression.

statements: Group of statements that are executed once if the expression matches the label.

Example:

In the following example, switch statement is used to display the marks range against a particular grade.

HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>JavaScript Switch statement : Example-1</title>
<link rel="stylesheet" type="text/css" href="example.css">
</head>
<body>
<h1>JavaScript : switch statement</h1>
<form name="form1" action ="#">
Input Grade type : <input type="text" name="text1" value="A" />
<br /><br />
<input type="button" value="Marks check"
onclick='marksgrade()' />
</form>
<script src="switch-statement-example1.js"></script>
</body>
</html>

JS Code

function marksgrade()
{
grade = document.form1.text1.value;
switch (grade)
{
case 'A+':
console.log("Marks >= 90");
break;
case 'A':
console.log("Marks [ >= 80 and <90 ]");
break;
case 'B+':
console.log("Marks [ >= 70 and <80 ]");
break;
case 'B':
console.log("Marks [ >= 60 and <70 ]");
break;
case 'C':
console.log("Marks < 60");
break;
default:
console.log("Wrong grade.........");
}
}

View the example in the browser

Practice the example online

See the Pen switch-1 by w3resource (@w3resource) on CodePen.


Previous: JavaScript: if...else statements
Next: JavaScript do while loop



JavaScript: Tips of the Day

JavaScript: Performs left-to-right function composition for asynchronous functions

Example:

const pipeAsyncFunctions = (...fns) => arg => fns.reduce((p, f) => p.then(f), Promise.resolve(arg));
const sum = pipeAsyncFunctions(
  a => a + 1,
  a => new Promise(resolve => setTimeout(() => resolve(a + 2), 1000)),
  a => a + 3,
  async a => (await a) + 4
);
(async () => {
  console.log(await sum(5)); 
})();

Output:

15