Chapter 5 Beginner 56 Questions

Practice Questions — Conditional Statements (if, else, switch)

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8 Easy

13 Medium

11 Hard

Topic-Specific Questions

Question 1

Easy

What is the output?

let x = 10;
if (x > 5) {
  console.log("Big");
}
console.log("Done");

The if block runs because x > 5 is true. The last line runs regardless.

Big
Done

Question 2

Easy

What is the output?

let age = 12;
if (age >= 18) {
  console.log("Adult");
} else {
  console.log("Minor");
}

12 is not >= 18.

Minor

Question 3

Easy

What is the output?

let score = 85;
if (score >= 90) {
  console.log("A");
} else if (score >= 80) {
  console.log("B");
} else if (score >= 70) {
  console.log("C");
} else {
  console.log("F");
}

85 is not >= 90, but it IS >= 80.

B

Question 4

Medium

What is the output?

let x = 0;
if (x) {
  console.log("Truthy");
} else {
  console.log("Falsy");
}

if checks for truthy/falsy, not just true/false. What is Boolean(0)?

Falsy

Question 5

Medium

What is the output?

let name = "";
if (name) {
  console.log(`Hello, ${name}!`);
} else {
  console.log("Name is empty.");
}

Empty string is falsy.

Name is empty.

Question 6

Medium

What is the output?

let color = "red";
switch (color) {
  case "red":
    console.log("Stop");
    break;
  case "yellow":
    console.log("Slow down");
    break;
  case "green":
    console.log("Go");
    break;
  default:
    console.log("Unknown");
}

color matches 'red'. break prevents fall-through.

Stop

Question 7

Medium

What is the output?

let num = 2;
switch (num) {
  case 1:
    console.log("One");
  case 2:
    console.log("Two");
  case 3:
    console.log("Three");
  default:
    console.log("Default");
}

There are no break statements. What happens after case 2 matches?

Two
Three
Default

Question 8

Hard

What is the output?

let x = "1";
switch (x) {
  case 1:
    console.log("Number one");
    break;
  case "1":
    console.log("String one");
    break;
  default:
    console.log("No match");
}

switch uses === (strict equality). '1' is not the same as 1.

String one

Question 9

Easy

Priya wrote this code but both messages print. Find the bug:

let score = 50;
if (score >= 90)
  console.log("Grade A");
  console.log("Excellent!");

Without curly braces, only the first line belongs to the if.

Add curly braces:

if (score >= 90) {
  console.log("Grade A");
  console.log("Excellent!");
}

Question 10

Hard

What is the output?

let a = 5;
let b = 10;
let c = 15;

if (a > b) {
  if (b > c) {
    console.log("A");
  } else {
    console.log("B");
  }
} else {
  if (a + b > c) {
    console.log("C");
  } else {
    console.log("D");
  }
}

5 > 10 is false, so go to the outer else. Then check 5 + 10 > 15.

D

Question 11

Easy

Write code that checks if a number stored in variable n (set to 7) is even or odd. Print the result.

Use the % operator: n % 2 === 0 means even.

let n = 7;
if (n % 2 === 0) {
  console.log(`${n} is even`);
} else {
  console.log(`${n} is odd`);
}

Output: 7 is odd

Question 12

Medium

What is the output?

let x = 5;
if (x > 3) {
  console.log("A");
}
if (x > 4) {
  console.log("B");
}
if (x > 5) {
  console.log("C");
}

These are separate if statements (not else-if), so each is checked independently.

A
B

Question 13

Hard

What is the output?

let n = 15;
if (n % 3 === 0 && n % 5 === 0) {
  console.log("FizzBuzz");
} else if (n % 3 === 0) {
  console.log("Fizz");
} else if (n % 5 === 0) {
  console.log("Buzz");
} else {
  console.log(n);
}

15 is divisible by both 3 and 5. Which condition is checked first?

FizzBuzz

Question 14

Medium

Write a switch statement that takes a month number (1-12) and prints the season: 'Winter' (12,1,2), 'Spring' (3,4,5), 'Summer' (6,7,8), 'Autumn' (9,10,11). Test with month = 7.

Use fall-through by grouping cases without break.

let month = 7;
switch (month) {
  case 12: case 1: case 2:
    console.log("Winter");
    break;
  case 3: case 4: case 5:
    console.log("Spring");
    break;
  case 6: case 7: case 8:
    console.log("Summer");
    break;
  case 9: case 10: case 11:
    console.log("Autumn");
    break;
  default:
    console.log("Invalid month");
}

Output: Summer

Question 15

Hard

What is the output?

let x = null;
if (x === null) {
  console.log("A");
}
if (x === undefined) {
  console.log("B");
}
if (x == undefined) {
  console.log("C");
}
if (!x) {
  console.log("D");
}

null === null is true. null === undefined is false. null == undefined is true. null is falsy.

A
C
D

Question 16

Hard

Write an HTML page with an input for temperature (in Celsius) and a button. When clicked, change the body's background color: red if >40, orange if >30, green if >15, blue if >0, purple if <=0.

Use document.body.style.backgroundColor and if-else.

<input type="number" id="temp" placeholder="Temperature (C)">
<button onclick="update()">Update</button>
<p id="msg"></p>
<script>
  function update() {
    let t = Number(document.getElementById("temp").value);
    let color;
    if (t > 40) color = "#e74c3c";
    else if (t > 30) color = "#f39c12";
    else if (t > 15) color = "#2ecc71";
    else if (t > 0) color = "#3498db";
    else color = "#9b59b6";
    document.body.style.backgroundColor = color;
    document.getElementById("msg").textContent = `${t} C`;
    document.getElementById("msg").style.color = "white";
  }
</script>

Question 17

Medium

What is the output?

let day = "Monday";
switch (day) {
  case "Saturday":
  case "Sunday":
    console.log("Weekend");
    break;
  default:
    console.log("Weekday");
    break;
}

Monday does not match Saturday or Sunday.

Weekday

Question 18

Medium

Rohan's code always prints 'Fail' even when marks is 85. Find the bug:

let marks = 85;
if (marks >= 90) {
  console.log("Grade A");
} else if (marks >= 80) {
  console.log("Grade B");
} else if (marks >= 40) {
  console.log("Pass");
}
if (marks < 40) {
  console.log("Fail");
} else {
  console.log("Fail");  // BUG: this always prints when marks >= 40!
}

Look at the second if-else block. When marks is 85, which branch runs?

The second if-else is a separate block. When marks >= 40, the else of the second block runs and prints "Fail". Fix by combining into one else-if chain or removing the second block.

Question 19

Hard

What is the output?

let a = "10";
let b = "9";
if (a > b) {
  console.log("a is greater");
} else {
  console.log("b is greater");
}

Both are strings. String comparison is character by character.

b is greater

Question 20

Easy

What is the output?

let x = 5;
let result = x > 3 ? "big" : "small";
console.log(result);

5 > 3 is true, so the ternary returns the first option.

big

Mixed & Application Questions

Question 1

Easy

What is the output?

let temp = 25;
if (temp > 30) {
  console.log("Hot");
} else if (temp > 20) {
  console.log("Warm");
} else {
  console.log("Cold");
}

25 is not > 30, but it IS > 20.

Warm

Question 2

Easy

Write code that checks if a year (2024) is a leap year. A year is a leap year if: divisible by 4 AND (not divisible by 100 OR divisible by 400).

Use % for divisibility and && / || for combining conditions.

let year = 2024;
if ((year % 4 === 0 && year % 100 !== 0) || year % 400 === 0) {
  console.log(`${year} is a leap year`);
} else {
  console.log(`${year} is not a leap year`);
}

Output: 2024 is a leap year

Question 3

Medium

What is the output?

let val = "";
if (val) {
  console.log("Has value");
} else if (val === "") {
  console.log("Empty string");
} else {
  console.log("Something else");
}

Empty string is falsy, so the first condition is false.

Empty string

Question 4

Medium

What is the output?

for (let i = 1; i <= 5; i++) {
  if (i === 3) {
    continue;
  }
  console.log(i);
}

continue skips the rest of the loop body for the current iteration.

1
2
4
5

Question 5

Medium

Write an HTML page with a text input for a password. As the user types (oninput), show feedback: 'Weak' (red) if < 6 chars, 'Medium' (orange) if 6-9 chars, 'Strong' (green) if >= 10 chars.

Use the .length property of the input value and if-else for feedback.

<input type="text" id="pass" oninput="check()" placeholder="Enter password">
<p id="feedback"></p>
<script>
  function check() {
    let len = document.getElementById("pass").value.length;
    let fb = document.getElementById("feedback");
    if (len === 0) {
      fb.textContent = "";
    } else if (len < 6) {
      fb.textContent = "Weak";
      fb.style.color = "red";
    } else if (len < 10) {
      fb.textContent = "Medium";
      fb.style.color = "orange";
    } else {
      fb.textContent = "Strong";
      fb.style.color = "green";
    }
  }
</script>

Question 6

Hard

What is the output?

let x = 10;
let y = 20;
let z = 30;

if (x < y && y < z) {
  console.log("Ascending");
}
if (x < y || x > z) {
  console.log("At least one true");
}
if (!(x === 10)) {
  console.log("Not ten");
} else {
  console.log("It is ten");
}

Evaluate each condition step by step. These are separate if blocks.

Ascending
At least one true
It is ten

Question 7

Hard

What is the output?

function check(val) {
  if (typeof val === "number") {
    if (val > 0) return "positive number";
    if (val < 0) return "negative number";
    return "zero";
  } else if (typeof val === "string") {
    if (val.length > 0) return "non-empty string";
    return "empty string";
  }
  return "other type";
}

console.log(check(42));
console.log(check(-5));
console.log(check(""));
console.log(check(null));

typeof null is 'object', not 'number' or 'string'.

positive number
negative number
empty string
other type

Question 8

Hard

Vikram's switch statement should print the Indian season but prints the wrong one for month 4. Find the bug:

let month = 4;
switch (month) {
  case 3: case 4: case 5:
    console.log("Summer");
    break;
  case 6: case 7: case 8: case 9:
    console.log("Monsoon");
    break;
  case 10: case 11:
    console.log("Autumn");
    break;
  case 12: case 1: case 2:
    console.log("Winter");
    break;
  default:
    console.log("Spring");
}

In India, April (4) is Summer. The code does print 'Summer' for month 4. Look more carefully at the season mapping.

The code actually works correctly for month 4 (prints Summer). If Vikram expected "Spring" for April, the mapping is wrong. In India, March-May is typically Summer, not Spring. The code matches the Indian season calendar correctly.

Question 9

Hard

Write a function that takes a number and returns its English ordinal suffix: 1st, 2nd, 3rd, 4th, 5th, ... 11th, 12th, 13th, 21st, 22nd, 23rd, 31st. Test with 1, 2, 3, 4, 11, 13, 21, 22.

The tricky part is 11, 12, 13 which all use 'th' (not st, nd, rd).

function ordinal(n) {
  let suffix;
  if (n % 100 >= 11 && n % 100 <= 13) {
    suffix = "th";
  } else {
    switch (n % 10) {
      case 1: suffix = "st"; break;
      case 2: suffix = "nd"; break;
      case 3: suffix = "rd"; break;
      default: suffix = "th";
    }
  }
  return n + suffix;
}
console.log(ordinal(1));   // 1st
console.log(ordinal(2));   // 2nd
console.log(ordinal(3));   // 3rd
console.log(ordinal(4));   // 4th
console.log(ordinal(11));  // 11th
console.log(ordinal(13));  // 13th
console.log(ordinal(21));  // 21st
console.log(ordinal(22));  // 22nd

Question 10

Medium

What is the output?

let x = 5;
let y = "5";

if (x == y) console.log("A");
if (x === y) console.log("B");
if (x != y) console.log("C");
if (x !== y) console.log("D");

== converts types. === does not. Same applies to != vs !==.

A
D

Question 11

Medium

Write an HTML page with a dropdown select for a traffic light color (Red, Yellow, Green). When the selection changes, display the appropriate message and change a div's background to that color.

Use the onchange event on a select element and switch or if-else.

<select id="light" onchange="update()">
  <option value="red">Red</option>
  <option value="yellow">Yellow</option>
  <option value="green">Green</option>
</select>
<div id="signal" style="width:100px;height:100px;border-radius:50%;margin:20px;"></div>
<p id="msg"></p>
<script>
  function update() {
    let color = document.getElementById("light").value;
    let signal = document.getElementById("signal");
    let msg = document.getElementById("msg");
    signal.style.backgroundColor = color;
    switch (color) {
      case "red":
        msg.textContent = "STOP!";
        break;
      case "yellow":
        msg.textContent = "SLOW DOWN";
        break;
      case "green":
        msg.textContent = "GO!";
        break;
    }
  }
  update();
</script>

Question 12

Hard

What is the output?

let n = 0;

if (n) {
  console.log("truthy");
}

if (n === 0) {
  console.log("zero");
}

if (n == false) {
  console.log("loose false");
}

if (n === false) {
  console.log("strict false");
}

0 is falsy. 0 == false is true. 0 === false is false (different types).

zero
loose false

Multiple Choice Questions

MCQ 1

What does the if statement check?

A. Whether a variable exists
B. Whether a condition is truthy or falsy
C. Whether two values are the same type
D. Whether a loop should continue

Answer: B
B is correct. The if statement evaluates a condition. If the result is truthy (not just true, but any truthy value), the code block runs. If falsy, it is skipped.

MCQ 2

What is the else block for?

A. It runs when the if condition is true
B. It runs when the if condition is false
C. It runs every time
D. It is optional and runs before the if

Answer: B
B is correct. The else block runs only when the if condition is false (falsy). It provides the alternative path.

MCQ 3

What keyword exits a switch case?

A. exit
B. stop
C. break
D. end

Answer: C
C is correct. break exits the switch statement. Without it, execution falls through to the next case.

MCQ 4

What comparison does switch use?

A. == (loose equality)
B. === (strict equality)
C. = (assignment)
D. It depends on the type

Answer: B
B is correct. switch uses === (strict equality) to compare the expression with each case value. This means types must match.

MCQ 5

What happens when you omit break in a switch case?

A. An error occurs
B. The switch exits immediately
C. Execution falls through to the next case
D. The default case runs

Answer: C
C is correct. Without break, execution continues into the next case regardless of whether it matches. This is called "fall-through" and can be used intentionally to group cases.

MCQ 6

What is the output of: if ('') console.log('yes'); else console.log('no');

A. yes
B. no
C. Error
D. undefined

Answer: B
B is correct. An empty string '' is falsy in JavaScript. if ('') evaluates to false, so the else block runs, printing 'no'.

MCQ 7

In an else-if chain, how many blocks can execute?

A. All of them
B. At most one
C. At least one
D. Exactly two

Answer: B
B is correct. In an if / else-if / else chain, only the first matching condition's block runs. All subsequent blocks are skipped. If none match and there is no else, zero blocks run.

MCQ 8

What is the output of: console.log('10' < '9')?

A. true
B. false
C. Error
D. NaN

Answer: A
A is correct. Both values are strings, so JavaScript compares them character by character. '1' (from '10') has a lower Unicode value than '9', so '10' < '9' is true. To compare as numbers, convert first.

MCQ 9

When should you use switch instead of if-else?

A. When you have only two conditions
B. When comparing one value against many specific values
C. When you need to check ranges (> or <)
D. Always, because switch is faster

Answer: B
B is correct. Switch is ideal when checking one variable against many specific values (like days of the week or color names). For range checks (>, <, >=), if-else is more appropriate. Switch does not support range comparisons directly.

MCQ 10

What is the output of: if ([] == false) console.log('yes'); else console.log('no');

A. yes
B. no
C. Error
D. undefined

Answer: A
A is correct. With ==, the array [] is converted to a string "", then to number 0. false is also converted to 0. 0 == 0 is true. However, if ([]) would be truthy because [] is an object. This shows why == is confusing.

MCQ 11

What happens if you write: if (x = 5) { ... }?

A. Checks if x equals 5
B. Assigns 5 to x, and the block always runs (5 is truthy)
C. Syntax error
D. Assigns 5 to x, and the block never runs

Answer: B
B is correct. x = 5 is assignment, not comparison. It assigns 5 to x and evaluates to 5. Since 5 is truthy, the if block always runs. This is a common bug — use === for comparison.

MCQ 12

In a switch, what is the default case?

A. The first case that runs
B. The case that runs when no other case matches
C. The case that always runs
D. A required part of every switch

Answer: B
B is correct. default runs when no case matches, similar to else in if-else. It is optional — you do not have to include it, but it is good practice for handling unexpected values.

MCQ 13

What is the ternary operator syntax?

A. condition : valueIfTrue ? valueIfFalse
B. condition ? valueIfTrue : valueIfFalse
C. if condition then value else value
D. condition && valueIfTrue || valueIfFalse

Answer: B
B is correct. The ternary syntax is condition ? valueIfTrue : valueIfFalse. The ? separates the condition from the true value, and : separates the true and false values.

MCQ 14

What is the output of: let x = 0; if (x !== false) console.log('yes'); else console.log('no');

A. yes
B. no
C. Error
D. undefined

Validate inputs. Show 2 decimal places. Use if-else for categories.

<!DOCTYPE html>
<html>
<body>
  <h2>BMI Calculator</h2>
  <input id="weight" type="number" placeholder="Weight (kg)"><br>
  <input id="height" type="number" placeholder="Height (cm)"><br>
  <button onclick="calcBMI()">Calculate</button>
  <h3 id="result"></h3>
  <p id="tip"></p>
  <script>
    function calcBMI() {
      let weight = Number(document.getElementById('weight').value);
      let height = Number(document.getElementById('height').value);
      let resultEl = document.getElementById('result');
      let tipEl = document.getElementById('tip');
      if (weight <= 0 || height <= 0) {
        resultEl.textContent = 'Please enter valid values.';
        resultEl.style.color = 'red';
        tipEl.textContent = '';
        return;
      }
      let bmi = weight / ((height / 100) ** 2);
      let category, color, tip;
      if (bmi < 18.5) {
        category = 'Underweight';
        color = '#3498db';
        tip = 'Consider eating more nutritious meals and consulting a doctor.';
      } else if (bmi < 25) {
        category = 'Normal weight';
        color = '#2ecc71';
        tip = 'Great job! Maintain a balanced diet and regular exercise.';
      } else if (bmi < 30) {
        category = 'Overweight';
        color = '#f39c12';
        tip = 'Try increasing physical activity and reducing processed food.';
      } else {
        category = 'Obese';
        color = '#e74c3c';
        tip = 'Please consult a healthcare professional for guidance.';
      }
      resultEl.textContent = `BMI: ${bmi.toFixed(2)} - ${category}`;
      resultEl.style.color = color;
      tipEl.textContent = 'Tip: ' + tip;
    }
  </script>
</body>
</html>

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