Javascript · Conditional Statements
switch statements
The full text of this chapter, to read or revisit. To practise, do the exercises.
▶ Do the exercisesExercise 1 — The switch Statement
When you compare the same variable against many exact values, an
else if
chain gets repetitive. JavaScript has a cleaner tool for that:
switch
.
let codemonType = "water";
switch (codemonType) {
case "fire":
console.log("Pyrochu joins the battle!");
break;
case "water":
console.log("Aquachu joins the battle!");
break;
case "plant":
console.log("Florachu joins the battle!");
break;
}
switch
takes the value of
codemonType
and looks for the
case
that matches it exactly. Here it finds
case "water"
and runs its code. Try changing the type!
Exercise 2 — break and default
Two keywords make
switch
work properly:
1.
break
stops the switch after a case. Without it, JavaScript keeps running the next cases too — that's called fall-through!
2.
default
runs when no case matches, like a final
else
.
let attack = "unknown-move";
switch (attack) {
case "thunder":
console.log("Zap strikes!");
break;
case "flame":
console.log("Pyrochu burns!");
break;
default:
console.log("Nothing happens...");
}
// Now watch what happens WITHOUT break:
let berry = "red";
switch (berry) {
case "red":
console.log("Spicy!");
case "blue":
console.log("Sweet!");
case "green":
console.log("Sour!");
}
All three messages print! After matching
case "red"
, the code falls through every following case. Almost always, you want a
break
at the end of each case.
Exercise 3 — Predict the switch
What will this code print?
let badge = "silver";
switch (badge) {
case "gold":
console.log("Elite trainer");
break;
case "silver":
console.log("Confirmed trainer");
break;
default:
console.log("Rookie trainer");
}
Options
• ```Confirmed trainer```
• ```Elite trainer```
• ```Rookie trainer```
• ```Confirmed trainer``` then ```Rookie trainer```
Hint : Find the case matching the value exactly, and note that each case ends with a ```break```.
Exercise 4 — Complete the switch
Complete the potion dispenser with the three missing keywords.
let potion = "super";
____ (potion) {
____ "super":
console.log("Restores 50 HP");
break;
case "hyper":
console.log("Restores 100 HP");
break;
____:
console.log("Unknown potion");
}
Options: switch case default if when else
Hint : One keyword opens the structure, one introduces each value, one handles the "no match" situation.
Exercise 5 — The Missing break
The
break
after the first case was forgotten. What will this print?
let move = "splash";
switch (move) {
case "splash":
console.log("Water everywhere!");
case "bubble":
console.log("Bubbles float up!");
break;
case "dive":
console.log("Aquachu dives!");
break;
}
Options
• ```Water everywhere!``` then ```Bubbles float up!```
• Only ```Water everywhere!```
• All three messages
• An error
Hint : Without ```break```, execution continues into the next case... until it finally meets a ```break```.
Exercise 6 — Arena Doors
Each arena door leads to a different battle. Complete the switch so it works correctly, without fall-through.
let door = 2;
switch (door) {
case 1:
console.log("You face Rockachu!");
____;
case ____:
console.log("You face Shadowchu!");
break;
default:
console.log("The door is locked");
____
Options: break 2 } stop "2" )
Hint : ```door``` contains a number, so the case value must be a number too — switch compares strictly, like ```===```.
Exercise 7 — switch Keywords
Match each keyword with its role in a
switch
.
Items to match
• switch
• case
• break
• default
Definitions
• Opens the structure with the value to test
• One possible value to match
• Stops execution of the switch
• Runs when no case matches
Exercise 8 — switch or else if?
So when should you use which? Simple rule:
1.
switch
: one variable compared to exact values (
"fire"
,
"water"
,
1
,
2
...)
2.
else if
chain: conditions with ranges or logic (
hp > 50
,
level >= 10 && hasBadge
...)
// switch CANNOT do this:
// case hp > 50: ❌ not an exact value
// For ranges, use else if:
if (hp > 50) {
console.log("Strong");
} else if (hp > 20) {
console.log("Weak");
}
Strict Comparison
switch
compares with strict equality (
===
). So
case "5"
will never match the number
5
— types must match too!
Exercise 9 — Right Tool for the Job
Which situation is a perfect fit for a
switch
?
Options
• Displaying a menu action for each exact choice: ```"fight"```, ```"heal"```, ```"run"```
• Testing if HP is between 20 and 50
• Checking ```level >= 10 && hasBadge```
• Choosing between two values for one variable
Hint : ```switch``` shines when one variable is compared against a list of exact values.
Exercise 10 — The Move Selector
Build Zap's move selector with a
switch
on
move
:
1.
"thunder"
prints
"Zap uses Thunder! 40 damage"
2.
"spark"
prints
"Zap uses Spark! 20 damage"
3.
"charge"
prints
"Zap charges energy..."
4. any other value prints
"Zap doesn't know this move!"
Don't forget the
break
after each case!
Starter code
let move = "spark";
// Write your switch here