JS Switch

JavaScript Switch

Introduction

The switch statement evaluates an expression, matching the expression's value to a case clause, and executes statements associated with that case.

switch (expression) {
  case value1:
    // statements executed when the result of expression matches value1
    break;
  case value2:
    // statements executed when the result of expression matches value2
    break;
  ...
  case valueN:
    // statements executed when the result of expression matches valueN
    break;
  default:
    // statements executed when none of the values match the value of the expression
    break;
}

The optional break statement associated with each case label ensures that the program breaks out of switch once the matched statement is executed and continues execution at the statement following switch. If break is omitted, the program continues execution at the next statement in the switch statement.

MDN link | MSDN link

Examples

In the following example, if expr evaluates to "Bananas", the program matches the value with case "Bananas" and executes the associated statement. When break is encountered, the program breaks out of switch and executes the statement following switch. If break were omitted, the statement for case "Cherries" would also be executed.

switch (expr) {
  case "Oranges":
    console.log("Oranges are $0.59 a pound.");
    break;
  case "Apples":
    console.log("Apples are $0.32 a pound.");
    break;
  case "Bananas":
    console.log("Bananas are $0.48 a pound.");
    break;
  case "Cherries":
    console.log("Cherries are $3.00 a pound.");
    break;
  case "Mangoes":
  case "Papayas":
    console.log("Mangoes and papayas are $2.79 a pound.");
    break;
  default:
    console.log("Sorry, we are out of " + expr + ".");
}

console.log("Is there anything else you'd like?");

🚀 Run Code

The following example takes advantage of the fact that if there is no break below a case statement it will continue to execute the next case statement regardless if the case meets the criteria. Here, four different values ("Cow", "Giraffe", "Dog", "Pig") perform exactly the same operation.

var Animal = 'Giraffe';
switch (Animal) {
  case 'Cow':
  case 'Giraffe':
  case 'Dog':
  case 'Pig':
    console.log('This animal will go on Noah\'s Ark.');
    break;
  case 'Dinosaur':
  default:
    console.log('This animal will not.');
}

🚀 Run Code