JavaScript Switch Case Statement

JavaScript Switch Case Statement

1. Introduction The switch statement is a control flow statement in JavaScript that allows you to execute different code blocks based on different conditions. It provides a concise way to write multiple if...else statements and makes the code more readable and maintainable. The switch statement evaluates an expression and compares it with multiple cases, executing the code block that matches the evaluated value.

2. Syntax The syntax of the switch statement is as follows:

javascript
switch (expression) {
  case value1:
    // code block executed when expression matches value1
    break;
  case value2:
    // code block executed when expression matches value2
    break;
  ...
  case valueN:
    // code block executed when expression matches valueN
    break;
  default:
    // code block executed when expression doesn't match any case
    break;
}

3. Explanation

• The switch statement starts with the switch keyword, followed by the expression to be evaluated in parentheses.
• Inside the switch statement, you define multiple case blocks, each representing a possible value that the expression can match.
• When the expression matches a case value, the code block associated with that case is executed.
• The break statement is used to terminate the switch statement and prevent the execution of subsequent case blocks. Without the break statement, the code would continue to execute the following case blocks until a break is encountered or the switch statement ends.
• If none of the case values match the expression, the code block within the default case is executed (optional). The default case serves as a fallback option when no other case matches.

4. Example Let's consider an example that uses the switch statement to determine the day of the week based on a numerical input:

javascript
function getDayOfWeek(dayNumber) {
  let day;

  switch (dayNumber) {
    case 1:
      day = "Sunday";
      break;
    case 2:
      day = "Monday";
      break;
    case 3:
      day = "Tuesday";
      break;
    case 4:
      day = "Wednesday";
      break;
    case 5:
      day = "Thursday";
      break;
    case 6:
      day = "Friday";
      break;
    case 7:
      day = "Saturday";
      break;
    default:
      day = "Invalid day";
      break;
  }

  return day;
}

console.log(getDayOfWeek(3)); // Output: "Tuesday"
console.log(getDayOfWeek(8)); // Output: "Invalid day"

In the above example, the getDayOfWeek function takes a dayNumber as input and uses a switch statement to determine the corresponding day of the week. If the dayNumber matches one of the case values, the corresponding day is assigned to the day variable. Otherwise, the default case is executed, assigning the value "Invalid day" to the day variable. Finally, the function returns the determined day.

5. Conclusion The switch statement in JavaScript provides an efficient way to handle multiple possible values of an expression. By using case blocks, you can specify different code paths based on the evaluated value, resulting in cleaner and more readable code.