Skip to content

chapter-08.md

Latest commit

 

History

History
55 lines (42 loc) · 2.25 KB

chapter-08.md

File metadata and controls

55 lines (42 loc) · 2.25 KB

Switch case conditional

If statement is great, but if you have more than two if statements, maybe it's time to use switch statement instead. Just like if statement, switch statement is used to control the flow of a program. It evaluates a value, but instead of using if, it will use the case keyword. Here is an example of switch statement in action:

let age = 15;
switch (age) {
  case 10:
  console.log ('Age is 10');
  break;
  case 20:
  console.log ('Age is 20');
  break;
  default:
  console.log ('Age is neither 10 or 20');
}

The switch statement takes the variable in the parentheses (in this case, age) and then tries to match it with the provided case statements. If the variable value founds a matching case, the statements associated with the case will be executed.

A break keyword is used to break out of the switch evaluation, and it's common to use it at the end of case statements to prevent the execution of statements following a match. Let's try to omit these break keywords so that you understand what I mean:

let age = 10;
switch (age) {
  case 10:
  console.log ('Age is 10');
  case 20:
  console.log ('Age is 20');
  default:
  console.log ('Age is neither 10 or 20');
}

Run the code, then change the age variable to 20, then 25. JavaScript will execute all statements following the matching case without the break keyword.

One thing you might note is that the case keyword can only evaluates a very specific value, like true or 10, while if statements allow the use of comparison in its conditional, like age > 10.

Each control flow statement is situational, but one key point to note is that for very specific conditional, use the switch statement. For conditional that allow comparison, use the if statement.

Code exercise

Create a school's first grade test score grading system which give the following rewards:

  • Students that got an A will get the Ironman sticker
  • Students that got a B will get the Captain America sticker
  • Students that got a C will get the Spiderman sticker

Example output:

You got an A, so here is an Ironman sticker for you!
You got a B, so here is the Captain America sticker for you!
You got a C, study better and here is your Spiderman sticker!