The idea
The mutating/non-mutating split is the thing that actually causes bugs. sort and reverse mutate; map and filter do not; splice mutates and slice does not, and their names are one letter apart.
Lesson
No lesson built yet. The worked solutions below are the material it would be assembled from.
Questions (4)
| Question | Type | Difficulty | Drift | Accuracy |
|---|---|---|---|---|
| What does [1, 2, 3].map(x => x * 2) return, and what happens to the original array? | mcq | Easy -1.00 | — | — (0) |
| Which of these array methods MUTATES the array it is called on? | mcq | Moderate 0.20 | — | — (0) |
| What does [1, 2, 3, 4].reduce((a, b) => a + b, 10) evaluate to? | numeric | Hard 0.50 | — | — (0) |
| What does [10, 9, 1, 2].sort() return? | mcq | Hard 1.20 | — | — (0) |