Sort two arrays the same way

Question

For example, if I have these arrays:

var name = [\"Bob\",\"Tom\",\"Larry\"];
var age =  [\"10\", \"20\", \"30\"];

And I use name.sort

Answer 1

This solution (my work) sorts multiple arrays, without transforming the data to an intermediary structure, and works on large arrays efficiently. It allows passing arrays as a list, or object, and supports a custom compareFunction.

Usage:

let people = ["john", "benny", "sally", "george"];
let peopleIds = [10, 20, 30, 40];

sortArrays([people, peopleIds]);
[["benny", "george", "john", "sally"], [20, 40, 10, 30]] // output

sortArrays({people, peopleIds});
{"people": ["benny", "george", "john", "sally"], "peopleIds": [20, 40, 10, 30]} // output

Algorithm:

• Create a list of indexes of the main array (sortableArray)
• Sort the indexes with a custom compareFunction that compares the values, looked up with the index
• For each input array, map each index, in order, to its value

Implementation:

/**
 *  Sorts all arrays together with the first. Pass either a list of arrays, or a map. Any key is accepted.
 *     Array|Object arrays               [sortableArray, ...otherArrays]; {sortableArray: [], secondaryArray: [], ...}
 *     Function comparator(?,?) -> int   optional compareFunction, compatible with Array.sort(compareFunction)
 */
function sortArrays(arrays, comparator = (a, b) => (a < b) ? -1 : (a > b) ? 1 : 0) {
    let arrayKeys = Object.keys(arrays);
    let sortableArray = Object.values(arrays)[0];
    let indexes = Object.keys(sortableArray);
    let sortedIndexes = indexes.sort((a, b) => comparator(sortableArray[a], sortableArray[b]));

    let sortByIndexes = (array, sortedIndexes) => sortedIndexes.map(sortedIndex => array[sortedIndex]);

    if (Array.isArray(arrays)) {
        return arrayKeys.map(arrayIndex => sortByIndexes(arrays[arrayIndex], sortedIndexes));
    } else {
        let sortedArrays = {};
        arrayKeys.forEach((arrayKey) => {
            sortedArrays[arrayKey] = sortByIndexes(arrays[arrayKey], sortedIndexes);
        });
        return sortedArrays;
    }
}

See also https://gist.github.com/boukeversteegh/3219ffb912ac6ef7282b1f5ce7a379ad