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Switch Statement Javascript — A Developer's Guide

February 11, 2026
javascript 

function getDayString(day) {
  switch (day) {
    case 0:
      return "Sunday";
    case 1:
      return "Monday";
    case 2:
      return "Tuesday";
    case 3:
      return "Wednesday";
    case 4:
      return "Thursday";
    case 5:
      return "Friday";
    case 6:
      return "Saturday";
    default:
      return "Invalid day";
  }
}
console.log(getDayString(3)); // Output: Wednesday
Wednesday

Don't you just love dealing with a gazillion if-else statements? I honestly prefer a cleaner way to handle conditionals - enter the switch statement JavaScript. If you've debugged this at 2am, you know what I mean.

How Switch Statements Work

A switch statement is essentially a fancy if-else chain. You specify an expression to evaluate and provide multiple cases to match against that expression's value. Here's the basic syntax:


switch (expression) {
  case value1:
    // code to execute
    break;
  case value2:
    // code to execute
    break;
  default:
    // default code to execute
}

The expression can be any valid JavaScript expression - a variable, a function call, or even a literal value. The values in each case must be unique.

Example: Using Switch Statements with Strings


function getGreeting(language) {
  switch (language) {
    case "English":
      return "Hello!";
    case "Spanish":
      return "Hola!";
    case "French":
      return "Bonjour!";
    default:
      return "Hello! (default)";
  }
}
console.log(getGreeting("Spanish")); // Output: Hola!
console.log(getGreeting("German")); // Output: Hello! (default)
Hola!
Hello! (default)

Notice how we're using strings as the values in our cases? This works beautifully for handling different languages or statuses.

Fallthrough Behavior

What happens when you forget the break; statement? Well, JavaScript will continue executing the next cases until it finds a break or reaches the end of the switch block.


function getDays() {
  let day = new Date().getDay();
  let message;
  
  switch (day) {
    case 0:
      message = "Sunday is ";
    case 6:
      message += "a weekend!";
      break;
    default:
      message = "Not a weekend.";
  }
  
  console.log(message);
}
getDays(); // Output depends on today's day
Not a weekend.

This fallthrough behavior can be both useful and error-prone - use it wisely!

Nested Switch Statements - Don't Do It!


function getTaxRate(state, incomeLevel) {
  switch (state) {
    case "CA":
      switch (incomeLevel) {
        case "high":
          return 10.5;
        default:
          return 8.5;
      }
    case "NY":
      switch (incomeLevel) {
        case "high":
          return 12;
        default:
          return 9;
      }
    default:
      throw new Error("Unsupported state");
  }
}
console.log(getTaxRate("CA", "high")); // Output: 10.5
10.5

Nested switches quickly become unreadable and unmaintainable. Trust me, your fellow devs won't thank you for this spaghetti code.

Type Coercion in Switch Statements

JavaScript's type coercion rules apply within switch statements too! So beware of implicit type conversions.


function guessType(x) {
  switch (x) {
    case null:
      console.log("null");
      break;
    case undefined:
      console.log("undefined");
      break;
    default:
      console.log(typeof x);
  }
}
guessType(null); // Output: null
guessType(undefined); // Output: undefined
guessType(NaN); // Output: number
guessType(false); // Output: boolean
guessType(0); // Output: number
guessType(""); // Output: string
null
undefined
number
boolean
number
string

This example showcases how switch statement JavaScript handles different data types.

switch statement javascript meme

Tips & Best Practices for Switch Statements in JavaScript

(just kidding!) But seriously: If your projects are running wild with unwieldy if-else chains and chunky switches, CodeConverter is here to help! Refactor those beasts into clean, manageable code anyone can read. Visit CodeConverter.co today and start writing better JavaScript!.

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