Question 1

True or false: JavaScript was originally developed in just 10 days by Brendan Eich.

Accepted Answer

True. Brendan Eich created the first version of JavaScript in May 1995 in only 10 days while at Netscape.

Question 2

True or false: JavaScript can accurately handle numbers like 0.1 + 0.2 without floating-point errors.

Accepted Answer

False. 0.1 + 0.2 equals 0.30000000000000004 due to IEEE 754 binary floating-point representation, a common gotcha.

Question 3

True or false: The '==' operator in JavaScript always performs type coercion before comparison.

Accepted Answer

False. '==' does coerce, but not always—if both operands are the same type, it behaves like '===' without coercion.

Question 4

True or false: JavaScript's 'Array.sort()' sorts numbers correctly by default without a compare function.

Accepted Answer

False. It sorts elements as strings by default, so [10, 2] becomes [10, 2] not [2, 10]. You must pass a numeric compare function.

Question 5

True or false: Using 'new Array(5)' creates an array with five undefined elements, not empty slots.

Accepted Answer

False. It creates an array with 5 empty slots (sparse array), not elements set to undefined. You need .fill() to populate them.

Question 6

True or false: The 'void' operator in JavaScript always returns the value 'undefined' regardless of operand.

Accepted Answer

True. 'void' evaluates its operand and returns undefined, commonly used to get the primitive undefined value safely.

Question 7

True or false: You can use 'undefined' as a variable name in modern JavaScript without causing an error.

Accepted Answer

True. 'undefined' is not a reserved word, so you can assign to it (e.g., var undefined = 10) in non-strict mode, though it's terrible practice.

Question 8

True or false: JavaScript's 'typeof null' returns 'object' due to a bug from the first version.

Accepted Answer

True. This is a long-standing bug where null is typed as 'object' because of a type tag error in the original 1995 implementation.

JavaScript Trivia Questions