JavaScript Switch

The switch statement evaluates an expression and match the expression's value to a case clause.

A switch statement can replace multiple if checks.
It gives a more descriptive way to compare a value with multiple variants.

Learn more about JavaScript Conditions

The JavaScript Switch Statement

Use the switch statement to select one of many code blocks to be executed.

The switch has one or more case blocks and an optional default block.

JS JavaScript - The JavaScript Switch Statement

switch(expression) {
   case x:
      code block
      break;
   case y:
      code block
      break;
   case z:
      code block
      break;
   default:
      code block
} 

This is how it works:

  • The switch expression is evaluated only once.
  • The value of the expression is compared with each case.
  • If any match, the associated block of code is executed.
  • If multiple cases match, the first case that matches is selected.

The break Keyword

When JavaScript reaches a break keyword, it breaks out of the switch block.

The break stops the execution of more code and case testing.

It is not necessary to break the last case in a switch block because the block ends anyway.


Learn more about JavaScript break

The default Keyword

The default keyword specifies the code to run if there is no case match.

There can only be one default keyword in a switch. Although this is optional, it is recommended that you use it, as it takes care of unexpected cases.


The JavaScript Switch Statement Example

JS JavaScript - The JavaScript Switch Statement Example

let input = 2 + 2;
 
switch (input) {
   case 3:
      alert( 'The value is too small' );
      break;
   case 4:
      // This line is executed
      alert( 'Exactly, you have a match!' );
      break;
   case 5:
      alert( 'The value is too large' );
      break;
   default:
      alert( "Sorry, there was no case match" );
}

The JavaScript Switch Statement Multi-Case Example

This example shows many cases with no break below the case statements. It will continue to execute the next case statement regardless if the case meets the criteria.

JS JavaScript - The JavaScript Switch Statement Multi-Case Example

var car = 'Tesla';
switch (car) {
   case 'Audi':
   case 'Tesla':
   case 'Mercedes':
   case 'Nissan':
      console.log('The company produce electric cars');
      break;
   case 'Ford':
   default:
      console.log('The company might produce electric cars in the near future');
}

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JS JavaScript: Switch

The switch statement evaluates an expression and match the expression's value to a case clause.

A switch statement can replace multiple if checks.
It gives a more descriptive way to compare a value with multiple variants.

JS JavaScript: Events

Events are actions or occurrences that happen to HTML elements.

JavaScript can act when an HTML Event occurs.

Events can represent everything from basic user interactions to automated notifications of things happening in the rendering model.

JS JavaScript: Strict Mode

The strict context prevents some actions and throws more exceptions. Strict mode changes previously accepted "bad syntax" into errors. Strict mode will for example prevent using undeclared variables. The "use strict" directive was new in ECMAScript version 5.

JS JavaScript: Var

Var is a keyword that is used to declare a variable.

But, you should NOT use var, use let when declaring a variable.

One of the most important things is that you should try to keep things simple!


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JavaScript is one of the 3 core language technologies of the World Wide Web that all web developers must learn:

1.      HTML to define the content of web pages.

2.      CSS to specify the layout of web pages.

3.      JavaScript to program the behavior of web pages.

JavaScript is a scripting or programming language that allows you to implement complex things on web pages. Every time a web page does more than just sit there and display static information for you to look at, displaying timely content updates, interactive maps, animated 2D/3D graphics, scrolling video jukeboxes, etc. − you can bet that JavaScript is probably involved.


The benefits of using JavaScript are:

1.      You can validate user input before sending the page off to the server. This saves server traffic, which means less load on your server.

2.      Immediate feedback to the visitors − They don't have to wait for a page reload to see if they have forgotten to enter something.

3.      Increased interactivity − You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard.

4.      Richer interfaces − You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.


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