PHP's usort in JavaScript

Here’s what our current JavaScript equivalent to PHP's usort looks like.

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module.exports = function usort (inputArr, sorter) {
// discuss at: http://locutus.io/php/usort/
// original by: Brett Zamir (http://brett-zamir.me)
// improved by: Brett Zamir (http://brett-zamir.me)
// note 1: This function deviates from PHP in returning a copy of the array instead
// note 1: of acting by reference and returning true; this was necessary because
// note 1: IE does not allow deleting and re-adding of properties without caching
// note 1: of property position; you can set the ini of "locutus.sortByReference" to true to
// note 1: get the PHP behavior, but use this only if you are in an environment
// note 1: such as Firefox extensions where for-in iteration order is fixed and true
// note 1: property deletion is supported. Note that we intend to implement the PHP
// note 1: behavior by default if IE ever does allow it; only gives shallow copy since
// note 1: is by reference in PHP anyways
// example 1: var $stuff = {d: '3', a: '1', b: '11', c: '4'}
// example 1: usort($stuff, function (a, b) { return (a - b) })
// example 1: var $result = $stuff
// returns 1: {0: '1', 1: '3', 2: '4', 3: '11'}

var valArr = []
var k = ''
var i = 0
var sortByReference = false
var populateArr = {}

if (typeof sorter === 'string') {
sorter = this[sorter]
} else if (Object.prototype.toString.call(sorter) === '[object Array]') {
sorter = this[sorter[0]][sorter[1]]
}

var iniVal = (typeof require !== 'undefined' ? require('../info/ini_get')('locutus.sortByReference') : undefined) || 'on'
sortByReference = iniVal === 'on'
populateArr = sortByReference ? inputArr : populateArr

for (k in inputArr) {
// Get key and value arrays
if (inputArr.hasOwnProperty(k)) {
valArr.push(inputArr[k])
if (sortByReference) {
delete inputArr[k]
}
}
}
try {
valArr.sort(sorter)
} catch (e) {
return false
}
for (i = 0; i < valArr.length; i++) {
// Repopulate the old array
populateArr[i] = valArr[i]
}

return sortByReference || populateArr
}
[ View on GitHub | Edit on GitHub | Source on GitHub ]

How to use

You you can install via npm install locutus and require it via require('locutus/php/array/usort'). You could also require the array module in full so that you could access array.usort instead.

If you intend to target the browser, you can then use a module bundler such as Browserify, webpack or rollup.js.

ES5/ES6

This function targets ES5, but as of Locutus 2.0.2 we also support ES6 functions. Locutus transpiles to ES5 before publishing to npm.

PHP arrays and JavaScript

Please note that Locutus uses JavaScript objects as substitutes for PHP arrays, they are the closest we can get to this hashtable-like data structure without rolling our own. While many JavaScript implementations preserve the order of object properties, the ECMAScript Language Specification explicitly states that:

The mechanics and order of enumerating the properties is not specified.

So don't use this for anything serious if you rely on the order to be consistent accross platforms.

A community effort

Not unlike Wikipedia, Locutus is an ongoing community effort. Our philosophy follows The McDonald’s Theory. This means that we don't consider it to be a bad thing that many of our functions are first iterations, which may still have their fair share of issues. We hope that these flaws will inspire others to come up with better ideas.

This way of working also means that we don't offer any production guarantees, and recommend to use Locutus inspiration and learning purposes only.

Notes

  • This function deviates from PHP in returning a copy of the array instead of acting by reference and returning true; this was necessary because IE does not allow deleting and re-adding of properties without caching of property position; you can set the ini of “locutus.sortByReference” to true to get the PHP behavior, but use this only if you are in an environment such as Firefox extensions where for-in iteration order is fixed and true property deletion is supported. Note that we intend to implement the PHP behavior by default if IE ever does allow it; only gives shallow copy since is by reference in PHP anyways

Examples

Please note that these examples are distilled from test cases that automatically verify our functions still work correctly. This could explain some quirky ones.

#codeexpected result
1var $stuff = {d: '3', a: '1', b: '11', c: '4'} usort($stuff, function (a, b) { return (a - b) }) var $result = $stuff{0: '1', 1: '3', 2: '4', 3: '11'}

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