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Arrays
mediumComplete guide with examples and interview questions · 30 min
Definition
Say it out loud in an interview — clear, simple, no textbook wording.
An array is an ordered list backed by an object with a length property. JavaScript arrays are dynamic — you can push, pop, and sparse gaps are allowed.
Senior interviews focus on immutability vs mutation and choosing the right iteration method.
Quick Stats
30
Minutes
medium
Difficulty
4
Interview Q's
Key takeaways
- •Arrays are objects with integer-like keys and a length property
- •Mutating methods (push, splice) change the array in place
- •map, filter, reduce are the core functional trio
- •sparse arrays have empty slots that map and forEach skip
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