1. What is typeof null ? Junior A. a historical bug where typeof returns 'object' for null B. == coerces operands to a common type before comparing; === compares value and type with no coercion C. a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it D. the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy
2. Which term means: "a historical bug where typeof returns 'object' for null"? Junior A. Falsy values B. == vs === C. Primitive types D. typeof null
3. Which statement is correct? Junior A. typeof null — the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint B. typeof null — a unique immutable primitive, typically used as a non-colliding object property key C. typeof null — a historical bug where typeof returns 'object' for null D. typeof null — a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it
4. What is Primitive types ? Junior A. the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy B. the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint C. a historical bug where typeof returns 'object' for null D. a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it
5. Which term means: "the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint"? Junior A. Falsy values B. Symbol C. == vs === D. Primitive types
6. Which statement is correct? Junior A. Primitive types — a unique immutable primitive, typically used as a non-colliding object property key B. Primitive types — a historical bug where typeof returns 'object' for null C. Primitive types — the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy D. Primitive types — the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint
7. What is == vs === ? Junior A. == coerces operands to a common type before comparing; === compares value and type with no coercion B. a unique immutable primitive, typically used as a non-colliding object property key C. a historical bug where typeof returns 'object' for null D. the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy
8. Which term means: "== coerces operands to a common type before comparing; === compares value and type with no coercion"? Junior A. typeof null B. Falsy values C. == vs === D. Primitive types
9. Which statement is correct? Junior A. == vs === — a historical bug where typeof returns 'object' for null B. == vs === — the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy C. == vs === — a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it D. == vs === — == coerces operands to a common type before comparing; === compares value and type with no coercion
10. What is NaN ? Mid A. a historical bug where typeof returns 'object' for null B. the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy C. the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint D. a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it
11. Which term means: "a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it"? Mid A. NaN B. typeof null C. Falsy values D. == vs ===
12. Which statement is correct? Mid A. NaN — a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it B. NaN — the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint C. NaN — a unique immutable primitive, typically used as a non-colliding object property key D. NaN — == coerces operands to a common type before comparing; === compares value and type with no coercion
13. What is Falsy values ? Junior A. the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint B. a historical bug where typeof returns 'object' for null C. the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy D. a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it
14. Which term means: "the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy"? Junior A. typeof null B. == vs === C. Primitive types D. Falsy values
15. Which statement is correct? Junior A. Falsy values — the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy B. Falsy values — == coerces operands to a common type before comparing; === compares value and type with no coercion C. Falsy values — a historical bug where typeof returns 'object' for null D. Falsy values — the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint
16. What is Symbol ? Mid A. == coerces operands to a common type before comparing; === compares value and type with no coercion B. a unique immutable primitive, typically used as a non-colliding object property key C. a historical bug where typeof returns 'object' for null D. the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy
17. Which term means: "a unique immutable primitive, typically used as a non-colliding object property key"? Mid A. Symbol B. Falsy values C. Primitive types D. == vs ===
18. Which statement is correct? Mid A. Symbol — a numeric value meaning 'not a number'; NaN !== NaN, so Number.isNaN is used to test for it B. Symbol — a unique immutable primitive, typically used as a non-colliding object property key C. Symbol — the 7 immutable value types: string, number, boolean, null, undefined, symbol, bigint D. Symbol — the values false, 0, '', null, undefined, NaN and 0n — everything else is truthy