Switch statement in Javascript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of switch with fall-through

What is the output of the following code?

Javascript

const value = 2;
switch(value) {
  case 1:
    console.log('One');
  case 2:
    console.log('Two');
  case 3:
    console.log('Three');
    break;
  default:
    console.log('Default');
}

A Two\nThree

B One\nTwo\nThree

C Three

D Default

💡 Hint

Remember that without break, cases fall through to the next.

The switch starts at case 2 and prints 'Two'. Because there is no break, it continues to case 3 and prints 'Three'. Then it hits break and stops.

❓ Predict Output

intermediate

Switch with string cases

What will this code print?

Javascript

const fruit = 'apple';
switch(fruit) {
  case 'banana':
    console.log('Banana');
    break;
  case 'apple':
    console.log('Apple');
    break;
  case 'orange':
    console.log('Orange');
    break;
  default:
    console.log('Unknown fruit');
}

A Banana

B Unknown fruit

C Orange

D Apple

💡 Hint

Check which case matches the string exactly.

The variable fruit is 'apple', so the case 'apple' matches and prints 'Apple'.

❓ Predict Output

advanced

Switch with multiple cases and default

What is the output of this code snippet?

Javascript

const num = 5;
switch(num) {
  case 1:
  case 3:
  case 5:
    console.log('Odd');
    break;
  case 2:
  case 4:
    console.log('Even');
    break;
  default:
    console.log('Unknown');
}

A Unknown

B Odd

C Even

D SyntaxError

💡 Hint

Multiple cases can share the same code block.

Number 5 matches case 5, which shares the block printing 'Odd'.

❓ Predict Output

advanced

Switch with expression and type coercion

What will this code print?

Javascript

const val = '2';
switch(val) {
  case 1:
    console.log('Number 1');
    break;
  case 2:
    console.log('Number 2');
    break;
  case '2':
    console.log('String 2');
    break;
  default:
    console.log('Default');
}

A String 2

B Number 2

C Default

D Number 1

💡 Hint

Switch uses strict equality (===) to compare values.

The variable val is the string '2'. It matches case '2' exactly, so it prints 'String 2'.

🧠 Conceptual

expert

Behavior of switch with no matching case and no default

What happens when a switch statement has no matching case and no default case?

A It executes the first case by default.

B It throws a ReferenceError at runtime.

C The switch block is skipped and no code inside runs.

D It causes an infinite loop.

💡 Hint

Think about what happens if no case matches and no default is present.

If no case matches and there is no default, the switch block does nothing and continues after it.

Practice

1. What is the main purpose of a switch statement in JavaScript?

easy

A. To choose which block of code to run based on a value

B. To repeat a block of code multiple times

C. To define a function

D. To create a new variable

Solution

1. Step 1: Understand the role of switch

   A switch statement checks a value and runs code matching that value.

2. Step 2: Compare with other options

   Repeating code is for loops, defining functions is with function keyword, and variables use let/const/var.

3. Final Answer:

   To choose which block of code to run based on a value -> Option A

4. Quick Check:

   Switch = choose code by value [OK]

Hint: Switch picks code based on one value quickly [OK]

Common Mistakes:

• Confusing switch with loops
• Thinking switch defines functions
• Believing switch creates variables

2. Which of the following is the correct syntax to start a switch statement in JavaScript?

easy

A. switch value { }

B. switch { value }

C. switch (value) { }

D. switch: (value) { }

Solution

1. Step 1: Recall switch syntax

   The switch statement requires parentheses around the value and curly braces for cases: switch (value) { ... }

2. Step 2: Check each option

   switch (value) { } matches correct syntax; others miss parentheses or use wrong symbols.

3. Final Answer:

   switch (value) { } -> Option C

4. Quick Check:

   Correct switch syntax uses parentheses and braces [OK]

Hint: Switch needs (value) and {cases} to work [OK]

Common Mistakes:

• Omitting parentheses around value
• Using curly braces instead of parentheses
• Adding colon after switch keyword

3. What will be the output of this code?

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('Unknown day');
}

medium

A. Monday

B. Tuesday

C. Unknown day

D. Wednesday

Solution

1. Step 1: Match the value with cases

   The variable day is 3, so the switch looks for case 3.

2. Step 2: Identify executed case

   Case 3 matches and prints 'Wednesday', then break stops further checks.

3. Final Answer:

   Wednesday -> Option D

4. Quick Check:

   day=3 matches case 3 = Wednesday [OK]

Hint: Match value to case, break stops after match [OK]

Common Mistakes:

• Forgetting break causes fall-through
• Choosing default when case matches
• Mixing up case numbers and outputs

4. Find the error in this switch statement:

const color = 'red';
switch(color) {
  case 'red'
    console.log('Stop');
    break;
  case 'green':
    console.log('Go');
    break;
  default:
    console.log('Wait');
}

medium

A. Wrong variable name in switch

B. Missing colon ':' after case 'red'

C. Missing break after case 'red'

D. Missing default case

Solution

1. Step 1: Check case syntax

   Each case must end with a colon ':' after the value. Here, case 'red' misses the colon.

2. Step 2: Verify other parts

   Break is present after case 'red' block, variable name is correct, and default exists.

3. Final Answer:

   Missing colon ':' after case 'red' -> Option B

4. Quick Check:

   Case needs ':' after value [OK]

Hint: Each case must end with ':' before code [OK]

Common Mistakes:

• Omitting colon after case value
• Forgetting break causing fall-through
• Missing default case (not always error)

5. You want to print 'Weekend' for days 6 and 7, and 'Weekday' for days 1 to 5 using a switch. Which code correctly does this?

hard

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

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

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

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

Solution

1. Step 1: Group cases for weekend and weekday

   Cases 6 and 7 should print 'Weekend' with one console.log and break after.

2. Step 2: Group cases 1 to 5 for 'Weekday' with break

   Cases 1-5 print 'Weekday' and break to avoid fall-through.

3. Step 3: Check default for invalid days

   Default prints 'Invalid day' if no case matches.

4. Final Answer:

   switch(day) { case 6: case 7: console.log('Weekend'); break; case 1: case 2: case 3: case 4: case 5: console.log('Weekday'); break; default: console.log('Invalid day'); } -> Option A

5. Quick Check:

   Group cases, use break to stop fall-through [OK]

Hint: Group cases without code, break after last case [OK]

Common Mistakes:

• Missing break causing fall-through
• Repeating console.log in each case unnecessarily
• Omitting default case for invalid input