js switch case

Explanation of switch case in JavaScript

A switch case statement is a control flow statement in JavaScript that allows you to execute different code blocks based on different conditions. It provides an alternative to using multiple if-else statements.

The syntax of a switch case statement is as follows:

switch (expression) {
  case value1:
    // code block to be executed if expression matches value1
    break;
  case value2:
    // code block to be executed if expression matches value2
    break;
  case value3:
    // code block to be executed if expression matches value3
    break;
  default:
    // code block to be executed if expression doesn't match any of the cases
}

Here's an explanation of each step involved in a switch case statement:

  1. The switch keyword is followed by an expression in parentheses. This expression is evaluated, and its value is compared to the values specified in the case statements.

  2. The case keyword is followed by a value that is compared to the expression. If the expression matches the value, the code block associated with that case is executed.

  3. If a match is found, the code block associated with that case is executed. This code block can contain one or more statements.

  4. After executing the code block of a matched case, the break statement is used to exit the switch case statement. Without the break statement, the execution would continue to the next case, even if it doesn't match the expression.

  5. If none of the cases match the expression, the default case is executed (if present). The default case is optional and is used to specify the code block that should be executed when none of the cases match the expression.

  6. After executing the code block of a matched case or the default case, the switch case statement is exited.

It's important to note that the expression in the switch case statement can be of any data type, including numbers, strings, or variables.

Example:

let day = 3;
let dayName;

switch (day) {
  case 1:
    dayName = "Monday";
    break;
  case 2:
    dayName = "Tuesday";
    break;
  case 3:
    dayName = "Wednesday";
    break;
  case 4:
    dayName = "Thursday";
    break;
  case 5:
    dayName = "Friday";
    break;
  default:
    dayName = "Invalid day";
}

console.log(dayName); // Output: Wednesday

In this example, the value of the day variable is compared to different cases, and the corresponding dayName is assigned based on the match. Since day is 3, the code block associated with the case 3 is executed, and dayName is set to "Wednesday".