20 Tricky Truthy and Falsy Values in JavaScript with Solutions

20 Tricky Truthy and Falsy Values Questions in JavaScript

In JavaScript, the concept of truthy and falsy values plays a critical role in how the language evaluates expressions in conditional statements like if and while. Understanding how JavaScript interprets values is essential to writing cleaner and more predictable code.

Here are 20 tricky truthy and falsy questions designed to help you enhance your understanding of JavaScript's behavior in different conditions.

1. What will the following code log to the console?

if ('0') {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• A non-empty string, including '0', is considered truthy in JavaScript.

2. What will be the output of this code?

if ([]) {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• An empty array [] is truthy in JavaScript.

3. What is the result of this comparison?

console.log(null == undefined);

Answer: True

• null and undefined are loosely equal (==) but not strictly equal (===).

4. What will be the output of this code?

if (NaN) {
  console.log('True');
} else {
  console.log('False');
}

Answer: False

• NaN (Not-a-Number) is falsy in JavaScript.

5. What will this code log to the console?

if (false) {
  console.log('True');
} else {
  console.log('False');
}

Answer: False

• The value false is falsy.

6. What will this log to the console?

if (0) {
  console.log('True');
} else {
  console.log('False');
}

Answer: False

• The number 0 is falsy.

7. What will be the result of this comparison?

console.log('' == 0);

Answer: True

• An empty string '' is loosely equal to 0 (==), but not strictly equal (===).

8. What will be logged here?

if ('false') {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• Any non-empty string, including 'false', is truthy.

9. What will this code log to the console?

if (undefined) {
  console.log('True');
} else {
  console.log('False');
}

Answer: False

• undefined is falsy.

10. What will this log?

console.log([] == []);

Answer: False

• Arrays are reference types, so two different arrays are not loosely equal.

11. What will this code log to the console?

if (' ') {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• A string containing a space ' ' is truthy.

12. What will the following code output?

console.log(0 == false);

Answer: True

• 0 and false are loosely equal (==).

13. What will the following code output?

console.log([] == false);

Answer: True

• An empty array [] is loosely equal to false.

14. What will this code log?

if ({} == false) {
  console.log('True');
} else {
  console.log('False');
}

Answer: False

• An empty object {} is not loosely equal to false.

15. What will be the result of this code?

if (null) {
  console.log('True');
} else {
  console.log('False');
}

Answer: False

• null is falsy.

16. What will this log?

console.log(1 == true);

Answer: True

• 1 is loosely equal to true.

17. What will the following code print?

if (true) {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• true is truthy.

18. What will this code output?

console.log('0' == 0);

Answer: True

• The string '0' is loosely equal to the number 0.

19. What will this log to the console?

if (0 == '0') {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• 0 and '0' are loosely equal (==).

20. What will this code print?

if (false == '') {
  console.log('True');
} else {
  console.log('False');
}

Answer: True

• false is loosely equal to an empty string ''.

Summary of Key Falsy and Truthy Values in JavaScript:

• Falsy values: false, 0, "" (empty string), NaN, null, undefined.
• Truthy values: Everything that is not falsy (e.g., non-empty strings, non-zero numbers, objects, arrays).

These questions are designed to help you better understand how JavaScript evaluates values in conditional statements and expressions. Mastering this knowledge is essential for writing effective and bug-free code in JavaScript.

Thank you for reading!
I hope this blog helped you understand tricky truthy and falsy values in JavaScript. Stay tuned for more programming tips and insights.

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