JavaScript: Perform stable sorting of an array, preserving the initial indexes of items when their values are the same
JavaScript fundamental (ES6 Syntax): Exercise-137 with Solution
Write a JavaScript program to perform stable sorting of an array, preserving the initial indexes of items when their values are the same. Returns a new array instead of mutating the original array.
- Use Array.prototype.map() to pair each element of the input array with its corresponding index.
- Use Array.prototype.sort() and a compare function to sort the list, preserving their initial order if the items compared are equal.
- Use Array.prototype.map() to convert back to the initial array items.
- Does not mutate the original array, but returns a new array instead.
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
const stableSort = (arr, compare) =>
arr
.map((item, index) => ({ item, index }))
.sort((a, b) => compare(a.item, b.item) || a.index - b.index)
.map(({ item }) => item);
const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
console.log(stableSort(arr, () => 0));
Sample Output:
[0,1,2,3,4,5,6,7,8,9,10]
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-137-1 by w3resource (@w3resource) on CodePen.
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