How Does JavaScript\'s `Array.sort()` Algorithm Work Under the Hood?

JavaScript Array.sort Algorithm

The JavaScript Array.sort() function provides a versatile sorting mechanism for arrays, accommodating various arguments and functions. However, the default sorting algorithm is determined by the type of the array elements.

For Numeric Arrays

Numeric arrays or arrays containing primitive data types undergo sorting using the C standard library function std::qsort(). This function operates on some variation of the quicksort algorithm, typically introsort.

For Contiguous Arrays of Non-Numeric Type

Arrays comprising non-numeric data are first stringified and then sorted using mergesort or qsort. Stable sorting is ensured when mergesort is employed, while qsort is utilized in its absence.

For Other Array Types

Arrays with non-contiguous elements, known as sparse arrays, and likely even associative arrays, adopt different sorting methods. WebKit, the underlying engine powering browsers like Chrome and Safari, employs selection sort ("min" sort) or, in certain instances, AVL trees. Specific type-to-algorithm mappings are not explicitly documented and require tracing the code paths.

Future Considerations

A comment within the source code suggests the potential implementation of radix sort for arrays sorted by string value, aiming to improve time complexity. However, this optimization remains pending.

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