JavaScript array_reverse
Return input as a new array with the order of the entries reversed
1 2 3 4 56 7 8 9 1011 12 13 14 1516 17 18 19 | function array_reverse (array, preserve_keys) { // Return input as a new array with the order of the entries reversed // // version: 909.322 // discuss at: http://phpjs.org/functions/array_reverse // + original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net) // + improved by: Karol Kowalski // * example 1: array_reverse( [ 'php', '4.0', ['green', 'red'] ], true); // * returns 1: { 2: ['green', 'red'], 1: 4, 0: 'php'} var arr_len = array.length, newkey = 0, tmp_arr = {}, key = ''; preserve_keys = !!preserve_keys; for (key in array) { newkey = arr_len - key - 1; tmp_arr[preserve_keys ? key : newkey] = array[key]; } return tmp_arr; } |
Examples
Running
1 | array_reverse( [ 'php', '4.0', ['green', 'red'] ], true); |
Should return
1 | { 2: ['green', 'red'], 1: 4, 0: 'php'} |
Dependencies
No dependencies, you can use this function standalone.
Open syntax issues
php.js uses JsLint to help us keep our code consistent and prevent some common bugs.
Eventually we want all code to pass or at least take into consideration most fixes suggested by JsLint, following this JsLint configuration we’ve decided on.
Authors
Thanks to the following developers, you get to have array_reverse goodness in JavaScript.
frame
18 Nov '08 
hmm .. i have downloaded the lib again and now there are the missing functions included.. please ignore..
frame
18 Nov '08
Some functions are not included in php.js or php.min.js.. why?
do you forget to?
ex: file_exists, array_reserve
Also...
21 Mar '08
Also from the site I just mentioned, here's a function which returns a genuine array (this could probably be combined with your function to test for preserve_keys and if not present, return a genuine array?):
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| function array_reverse(arr) { /* Simulate copy by value */ var arr_rev = []; for (var i = 0; i < arr.length; i++) { arr_rev[i] = arr[i]; } arr_rev.reverse(); return arr_rev; } |
Brett Zamir
21 Mar '08
Seems you've already done a whole lot of work, but not knowing about your site, I had started a wiki to keep this kind of information: http://javascript.wikia.com/wiki/PHP-Javascript . There are a few functions there presently, but please feel free to consider hosting this at such a wiki so it can be easily maintained by the whole community! Thanks! Email me at brettz9 & yahoo if you like.
Kevin van Zonneveld
16 Feb '08
@ Karol Kowalski: That's solid work you can take pride in Karol, thank you!
Karol Kowalski
12 Feb '08
Hello,
I've done some code refactoring, making the code do what it really needs to do (there's no need for the 2nd loop, it there?). I've run a test and it seems to be 38% faster. Here's the code
1 2 3 4 56 7 8 9 1011 12 13 14 1516 17 18 19 2021 22 23 24 2526 27 28 29 3031 32 33 34 3536 37 38 39 4041 42 43 44 4546 47 48 49 5051 52 53 54 5556 57 58 59 6061 62 63 64 | function array_reverse( array, preserve_keys ) { // http://kevin.vanzonneveld.net // + original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net) // * example 1: array_reverse( [ 'php', '4.0', ['green', 'red'] ], true ); // * returns 1: { 2: ['green', 'red'], 1: 4, 0: 'php'} var i=0, f, key, keys = [], key_cnt=0, tmp_ar = {}; for(key in array){ keys[i++] = key; } keys = keys.reverse(); key_cnt = keys.length; for( i=0; i < key_cnt; i++ ){ tmp_ar[(preserve_keys ? keys[i] : i)] = array[keys[i]]; } return tmp_ar; } function array_reverse2( array, preserve_keys ) { // http://kevin.vanzonneveld.net // + original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net) // * example 1: array_reverse( [ 'php', '4.0', ['green', 'red'] ], true ); // * returns 1: { 2: ['green', 'red'], 1: 4, 0: 'php'} var arr_len=array.length, newkey=0, tmp_ar = {} for(var key in array){ newkey=arr_len-key-1; tmp_ar[(!!preserve_keys)?newkey:key]=array[newkey] } return tmp_ar;} // wrapped in windows onload cause // Firebug 1.1 throws an error otherwise window.onload=function () { console.time('array_reverse') for (var i=10000;i;i--) { array_reverse( [ 'php', '4.0', ['green', 'red'] ], true ); } console.timeEnd('array_reverse') console.time('array_reverse2') for (var i=10000;i;i--) { array_reverse2( [ 'php', '4.0', ['green', 'red'] ], true ); } console.timeEnd('array_reverse2') } |
Kevin van Zonneveld
18 Nov '08