Understanding Switch Case in JavaScript

JavaScript, as a versatile programming language, offers various tools and constructs to control the flow of your code. One such essential feature is the switch statement, which allows developers to execute different blocks of code based on different conditions. The switch statement is particularly useful when you have multiple conditions to evaluate against a single variable.


The syntax for a switch statement looks like this:

switch (expression) {
  case value1:
    // Code to be executed when expression matches value1
  case value2:
    // Code to be executed when expression matches value2
  // Additional cases as needed
    // Code to be executed if expression doesn't match any case
  • expression: The variable or value to be checked against different cases.
  • case value1: A specific value to compare against the expression.
  • break: Keyword to end the current case block and exit the switch statement.
  • default: An optional block of code to execute if none of the cases match the expression.

How Switch Case Works

When a switch statement is executed, the expression value is evaluated. JavaScript checks each case value against the expression. If a match is found, the code within that case block is executed until the break statement is encountered, exiting the switch block. If no match is found, the code within the default block (if provided) is executed.

Example Usage

Let’s consider a simple example to illustrate the usage of a switch statement in JavaScript:

let day = 3;
let dayName;

switch (day) {
  case 1:
    dayName = 'Monday';
  case 2:
    dayName = 'Tuesday';
  case 3:
    dayName = 'Wednesday';
  case 4:
    dayName = 'Thursday';
  case 5:
    dayName = 'Friday';
    dayName = 'Weekend';

console.log(`Today is ${dayName}`);

In this example, the variable day holds a value of 3. The switch statement evaluates day against different cases. Since day matches the value 3, the code within the case 3 block is executed, assigning dayName the value 'Wednesday'. The console.log() statement then displays Today is Wednesday.

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