Test your knowledge: JavaScript Values, Types, Coercion, and Equality

Review

1. Which item is an ECMAScript language type?

   Object is one of the language types; Date, Array, and Promise are objects.
2. Which value is falsy?

   The Number value 0 is falsy. The string "0", arrays, and objects are truthy.
3. What does Number("42") produce?

   Number converts the numeric string to the Number value 42.
4. Which is the specific NaN test?

   NaN is not equal to itself; Number.isNaN directly tests for the Number NaN value.
5. What is 42 === "42"?

   Strict equality does not coerce different types.
6. Why is 42 == "42" true?

   Abstract equality has defined conversion steps when operand types differ.
7. What is "10" < "2"?

   Both operands are strings, so string ordering is used.
8. What happens with 1n + 1?

   Number and BigInt cannot be mixed in ordinary arithmetic.
9. Which treats NaN as equal to itself?

   Object.is uses SameValue semantics, which considers NaN the same value as itself.
10. Why are {score: 10} === {score: 10} false?

    Each object literal creates a distinct object.