Can you guess the length? #shorts #javascript

Result 1: 11
Result 2: undefined
The Explanation:
Sparse Arrays: In JavaScript, when you assign a value to an index far beyond the current length (like index 10), JS doesn't fill the gaps with zeros. It creates a Sparse Array.
The "Holes": The indices from 3 to 9 become "empty slots" (also called holes).
Length Property: The .length of an array is always highest index + 1. Since our highest index is 10, the length becomes 11.
Accessing Holes: If you try to access one of these empty slots (like arr[5]), it returns undefined, even though the slot technically doesn't even "exist" in memory yet!
The Pro Tip: To avoid unexpected behavior with sparse arrays, always use methods like .push() or ensure your indices are sequential.
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