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 JavaScript Switch JAVASCRIPT

JavaScript Switch  


JavaScript Switch

The JavaScript Switch Statement

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

Syntax

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

This is how it works:

  • The switch expression is evaluated once.
  • The value of the expression is compared with the values of each case.
  • If there is a match, the associated block of code is executed.

The getDay() method returns the weekday as a number between 0 and 6. (Sunday=0, Monday=1, ...)

switch (new Date().getDay()) {
  case 0:
    day = "Sunday";
    break;
  case 1:
    day = "Monday";
    break;
  case 2:
     day = "Tuesday";
    break;
  case 3:
    day = "Wednesday";
    break;
  case 4:
    day = "Thursday";
    break;
  case 5:
    day = "Friday";
    break;
  case 6:
    day = "Saturday";
}

The break Keyword

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

This will stop the execution of the block.

It is not necessary to break the last case in a switch block. The block breaks (ends) there anyway.

The default Keyword

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

Example: The getDay() method returns the weekday as a number between 0 and 6.

switch (new Date().getDay()) {
  case 6:
    text = "Today is Saturday";
    break;
  case 0:
    text = "Today is Sunday";
    break;
  default:
    text = "Looking forward to the Weekend";
}

Strict Comparison

Switch cases use strict comparison (===).

The values must be of the same type to match.

A strict comparison can only be true if the operands are of the same type.

In this example there will be no match for x:

Example

var x = "0";
switch (x) {
  case 0:
    text = "Off";
    break;
  case 1:
    text = "On";
    break;
  default:
    text = "No value found";
}

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