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switch

switch

Introduction

The switch statement evaluates an expression and executes code based on matching cases. It’s cleaner than multiple if-else chains when comparing the same value.

Syntax

switch (expression) {
  case value1:
    // runs if expression === value1
    break;
  case value2:
    // runs if expression === value2
    break;
  default:
    // runs if no case matches
}

Visual Explanation

flowchart TD
    Exp["Day of week"]
    Mon["Monday → Work"]
    Tue["Tuesday → Work"]
    Sat["Saturday → Party"]
    Sun["Sunday → Rest"]
    Default["Invalid day"]

    Exp --> Mon
    Exp --> Tue
    Exp --> Sat
    Exp --> Sun
    Exp --> Default

Example

const day = 3;

switch (day) {
  case 1:
    console.log('Monday');
    break;
  case 2:
    console.log('Tuesday');
    break;
  case 3:
    console.log('Wednesday');
    break;
  default:
    console.log('Invalid day');
}

Fall-Through

switch (day) {
  case 1:
  case 2:
  case 3:
  case 4:
  case 5:
    console.log('Weekday');
    break;
  case 6:
  case 7:
    console.log('Weekend');
    break;
}

Summary

Use switch for multiple conditions on the same value
Always include break unless you want fall-through
default handles no-match cases

Further Reading

MDN: switch