The switch statement

Learn multi-way selection with switch, case, break and default.

switch: branching on a single value

The switch statement makes it easy to choose among many branches based on a variable's value. Each branch starts with a case label and a colon : to mark the value.

let season = 2;
switch (season) {
  case 1:
    console.log("Winter");
    break;
  case 2:
    console.log("Spring");
    break;
  default:
    console.log("Unknown");
}

JavaScript compares the value to each case and runs the first branch that matches. If no case matches, default runs.

default and fall through

The default branch runs when no case matches; it is optional but added for safety. If you forget break, JavaScript falls into the next case too; this is called fall through.

switch (day) {
  case 1:
  case 2:
    console.log("Weekday");
    break;
  default:
    console.log("Other");
}

Here case 1 and case 2 share the same output; this uses fall through on purpose. When accidental, it causes serious bugs.

Exercise Write a season switch

The season variable is a number from 1 to 4. Use switch to log the season name: 1 'Winter', 2 'Spring', 3 'Summer', 4 'Autumn'. For unknown values log 'Unknown'. Each case must end with break and there must be a default branch.

Show example solution

let season = 2;
switch (season) {
  case 1:
    console.log("Winter");
    break;
  case 2:
    console.log("Spring");
    break;
  case 3:
    console.log("Summer");
    break;
  case 4:
    console.log("Autumn");
    break;
  default:
    console.log("Unknown");
}

Test yourself

What does the break statement do inside a switch?
- Stops branching and exits the switch
- Starts a new case
- Restarts the switch
- Jumps to the default case
Show answer

Stops branching and exits the switch — Correct. break exits the switch statement and prevents later cases from running.

Write the case label

let day = 1;
switch (day) {
____ 1:
    console.log("Monday");
    break;
}

Show answer

let day = 1;
switch (day) {
case 1:
    console.log("Monday");
    break;
}

Match the switch parts

switch

Starts the statement
case

Tests a single value
break

Stops branching
default

Runs when nothing matches

Next lesson: The ternary operator

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