Is JavaScript's `Array.sort()` a Reliable Method for Shuffling Arrays?

Can You Rely on JavaScript Array.sort() for Shuffling?

The use of JavaScript's Array.sort() method for shuffling an array has sparked debate. While experimental results suggest its effectiveness, concerns remain regarding the method's correctness and impartiality.

Correctness

The efficacy of sort() for shuffling hinges on the sorting algorithm utilized. Given the absence of a specified sorting algorithm in the ECMA standard, different implementations may yield diverse results. While some algorithms may provide random shuffles, others might produce infinite loops.

Uniformity

Another concern is the method's uniformity in generating random sequences. Sorting algorithms like Bubblesort or Quicksort may inherently prioritize certain permutations over others, potentially skewing the distribution of results. Additionally, the sort() method's reliance on floating-point comparisons carried out by Math.random() introduces the possibility of uneven probabilities in the range [0;1[.

Alternatives

To ensure consistent and unbiased shuffling, implementing the Fisher-Yates algorithm is preferred. This approach involves iterative swapping through the array until all elements have been shuffled, resulting in an O(n) time complexity.

Summary

While Array.sort() may superficially appear to shuffle arrays effectively, its correctness and impartiality are subject to the underlying sorting algorithm's implementation. For reliable and uniform shuffling, the Fisher-Yates algorithm remains the recommended choice.

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