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@jherax jherax/sortBy.js
Last active Feb 15, 2019

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Sorts an array with multiple ordering criteria (Schwartzian transform)
/**
* Sorts an array and allows multiple sorting criteria.
*
* It applies the Schwartzian transform:
* https://en.wikipedia.org/wiki/Schwartzian_transform
*
* Author: David Rivera
* Github: https://github.com/jherax
*
* You can fork this project on github:
* https://github.com/jherax/array-sort-by.git
*/
const sortBy = (function() {
const accent = 'ÂâÀàÁáÄäÃãÅåÊêÈèÉéËëÎîÌìÍíÏïÔôÒòÓóÖöÕõÛûÙùÚúÜüÑñÝýÿ';
const normal = 'AaAaAaAaAaAaEeEeEeEeIiIiIiIiOoOoOoOoOoUuUuUuUuNnYyy';
const DESC = /^desc:\s*/i;
// Converts the accented characters to its equivalent with no accent
function ignoreAccent(text) {
const length = accent.length;
for (let i = 0; i < length; i += 1) {
text = text.replace(accent.charAt(i), normal.charAt(i));
}
// ignores case sensitive
return text.toUpperCase();
}
// Compares each element and defines the sorting order
function comparer(prev, next) {
let asc = 1;
if (typeof prev === 'string') {
if (DESC.test(prev)) asc = -1;
prev = ignoreAccent(prev);
next = ignoreAccent(next);
}
if (prev === next) return 0;
return (prev > next ? 1 : -1) * asc;
}
// Compares each decorated element
function sortItems(aprev, anext) {
let i, ordered;
for (i in aprev) { // eslint-disable-line
ordered = comparer(aprev[i], anext[i]);
if (ordered) return ordered;
}
return 0;
}
// Defines the default sort order (ASC)
function defaultSort(prev, next) {
if (typeof prev === 'string') {
prev = ignoreAccent(prev);
next = ignoreAccent(next);
}
if (prev === next) return 0;
return (prev > next ? 1 : -1);
}
/**
* Sorts an array and allows multiple sorting criteria.
*
* @param {Array} array: the collection to sort
* @param {Function} parser: transforms each item and specifies the sorting order
* @return {Array}
*/
return function sortBy(array, parser) {
let i, item;
const arrLength = array.length;
if (typeof parser === 'undefined') {
return array.sort(defaultSort);
}
// Schwartzian transform (decorate-sort-undecorate)
for (i = arrLength; i;) {
item = array[i -= 1];
// decorate the array
array[i] = [].concat(parser.call(null, item, i), item);
// console.log('decorated: ', array[i]);
}
// sort the array
array.sort(sortItems);
// undecorate the array
for (i = arrLength; i;) {
item = array[i -= 1];
array[i] = item[item.length - 1];
}
return array;
}
}());
/* UTILS */
function writeHeader(text, array) {
array && console.info(JSON.stringify(array));
console.warn(text);
}
function writeJSON(array) {
console.log(JSON.stringify(array, null, 2));
}
/* TEST */
var arr = [5, 1, 8, 0, 3, 7, 10, 4, 3, 8];
writeHeader("DEFAULT SORT (ASC)", arr);
writeJSON(sortBy(arr));
writeHeader("SORT (DESC)");
writeJSON(sortBy(arr, item => -item));
arr = ["1983/03/06", "1980/12/24", "1985/08/31", "1983/03/05"];
writeHeader("SORT ASC (as Date)", arr);
sortBy(arr, (item) => new Date(item));
writeJSON(arr);
writeHeader("SORT DESC (as String)");
sortBy(arr, (item) => "desc:" + item);
writeJSON(arr);
arr = [
{ id: 10, text: 'Woche' },
{ id: 20, text: 'wöchentlich' },
{ id: 30, text: 'wäre' }
];
writeHeader("SORTING ACCENTED WORDS BY @text");
sortBy(arr, (item) => item.text);
writeJSON(arr);
arr = [
{ a: 9, age: 26, name: "pedro" },
{ a: 6, age: 21, name: "Pedro" },
{ a: 7, age: 26, name: "Maria" },
{ a: 2, age: 26, name: "maría" }
];
writeHeader("SORT ASC BY @name, AFTER DESC BY @age, AFTER ASC BY @a", arr);
sortBy(arr, (item) => [item.name, -item.age, item.a]);
writeJSON(arr);
@jherax

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commented Oct 21, 2016

This is a global module version of the ES6 module in the following github repo:
https://github.com/jherax/array-sort-by

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