» Javascript equivalent for PHP's function_exists

399 PHP equivalents

PHP to Javascript Project: php.js

php.jsThis article is part of the 'Porting PHP to Javascript' Project, which aims to decrease the gap between developing for PHP & Javascript.

A lot of people are familiar with PHP's functions, and though Javascript functions are often quite similar, some functions may be missing or addressed differently. The Javascript implementations should be as compliant with the PHP versions as possible, a good indication is that the PHP function manual could also apply to the Javascript version.

Porting crucial PHP functions to Javascript can be fun & useful. Currently some PHP functions have been added, but readers are encouraged to contribute and improve functions by adding comments. Eventually the goal is to save all the functions in one php.js file and make it publicly available for your coding pleasure.

If you choose to contribute, let me know how you want to be credited in the function's comments. You may also want to subscribe to RSS so you receive updates whenever new functions are posted.

This is a Javascript version of the PHP function: function_exists.

I have moved out PHP.JS to it's own site. For info & reactions on comments please goto phpjs.org

PHP function_exists

Description

function_exists - Return TRUE if the given function has been defined

bool function_exists( string function_name )

Checks the list of defined functions, both built-in (internal) and user-defined, for function_name.

Parameters

  • function_name

    The function name, as a string.

Return Values

Returns TRUE if function_name exists and is a function, FALSE otherwise.

Note: This function will return FALSE for constructs, such as include_once() and echo().

See Also

Javascript function_exists

Source

This is the main source of the Javascript version of PHP's function_exists

function function_exists( function_name ) {
    // http://kevin.vanzonneveld.net
    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Steve Clay
    // +   improved by: Legaev Andrey
    // *     example 1: function_exists('isFinite');
    // *     returns 1: true
 
 
    if (typeof function_name == 'string'){
        return (typeof this.window[function_name] == 'function');
    } else{
        return (function_name instanceof Function);
    }
}

Examples

Currently there is 1 example

Example 1

This is how you could call function_exists()
function_exists('isFinite');
And that would return
true

More about this Project

Download php.js

To easily include it in your code, every function currently available is stored in

Normal

Namespaced What is 'namespaced?'

To download use Right click, Save Link As
Generally the best way is to use a minified version and gzip it


Credits

Respect & awards go to everybody who has contributed in some way so far:

medalmedalBrett Zamir (link) for contributing to:
 array_diff, array_diff_assoc, array_diff_key, array_diff_uassoc, array_diff_ukey, array_fill_keys, array_fill_keys, array_filter, array_intersect, array_intersect_assoc, array_intersect_key, array_intersect_uassoc, array_intersect_ukey, array_keys, array_map, array_merge, array_merge_recursive, array_pop, array_search, array_slice, array_slice, array_splice, array_udiff, array_udiff_assoc, array_udiff_uassoc, array_uintersect, array_uintersect_assoc, array_uintersect_uassoc, array_unique, arsort, arsort, asort, asort, compact, current, each, end, extract, key, krsort, ksort, natcasesort, natcasesort, natsort, natsort, next, pos, prev, reset, rsort, rsort, shuffle, sort, sort, uasort, uasort, uksort, usort, classkit_import, classkit_method_add, classkit_method_copy, classkit_method_redefine, classkit_method_remove, classkit_method_rename, class_exists, get_class_methods, get_class_vars, get_declared_classes, get_object_vars, method_exists, property_exists, ctype_alnum, ctype_alpha, ctype_cntrl, ctype_digit, ctype_graph, ctype_lower, ctype_print, ctype_punct, ctype_space, ctype_upper, ctype_xdigit, date, date, date, date, date_default_timezone_get, date_default_timezone_set, date_parse, gettimeofday, gmdate, gmmktime, gmstrftime, idate, localtime, mktime, strftime, strtotime, timezone_abbreviations_list, timezone_identifiers_list, restore_exception_handler, set_exception_handler, fclose, feof, fgetc, fgetcsv, fgets, fgetss, filemtime, fopen, fpassthru, fread, fseek, ftell, pathinfo, pclose, popen, readfile, rewind, call_user_func, call_user_func_array, create_function, func_get_arg, func_get_args, func_num_args, get_defined_functions, get_defined_functions, register_shutdown_function, assert, assert_options, get_cfg_var, get_defined_constants, get_required_files, getenv, getlastmod, ini_alter, ini_get, ini_get_all, ini_restore, ini_set, php_ini_loaded_file, php_ini_scanned_files, phpversion, putenv, set_time_limit, include, include_once, require, require_once, atan2, expm1, fmod, log1p, rand, constant, define, defined, die, exit, exit, php_strip_whitespace, sleep, time_nanosleep, time_sleep_until, usleep, gopher_parsedir, setrawcookie, aggregate, aggregate_info, aggregate_methods, aggregate_methods_by_list, aggregate_methods_by_regexp, aggregate_properties, aggregate_properties_by_list, aggregate_properties_by_regexp, aggregation_info, deaggregate, preg_grep, sql_regcase, runkit_class_adopt, runkit_class_emancipate, runkit_function_add, runkit_function_copy, runkit_function_redefine, runkit_function_remove, runkit_function_rename, runkit_import, runkit_method_add, runkit_method_copy, runkit_method_redefine, runkit_method_remove, runkit_method_rename, runkit_superglobals, chunk_split, convert_uuencode, count_chars, echo, get_html_translation_table, lcfirst, levenshtein, localeconv, md5, md5_file, nl2br, nl_langinfo, parse_str, printf, quoted_printable_decode, quoted_printable_decode, quoted_printable_encode, setlocale, sha1, soundex, sprintf, str_getcsv, str_ireplace, str_replace, str_replace, str_shuffle, str_split, str_word_count, strcoll, strcspn, strip_tags, strlen, strnatcasecmp, strncmp, strrchr, strspn, strtok, strtr, substr_compare, substr_replace, ucfirst, vprintf, base64_decode, get_headers, get_meta_tags, parse_url, rawurldecode, rawurldecode, rawurlencode, rawurlencode, rawurlencode, urldecode, urldecode, urlencode, urlencode, doubleval, get_defined_vars, get_resource_type, gettype, import_request_variables, import_request_variables, is_array, is_array, is_binary, is_buffer, is_callable, is_real, is_resource, is_unicode, print_r, print_r, settype, strval, strval, unserialize, var_dump, var_export, utf8_decode
spacemedalOnno Marsman for contributing to:
 acos, acosh, asin, asinh, atan, atanh, ceil, cos, cosh, decbin, dechex, decoct, exp, floor, fmod, getrandmax, hypot, is_finite, is_infinite, is_nan, lcg_value, log, log10, max, max, min, min, mt_getrandmax, mt_rand, pi, pow, rand, round, sin, sinh, sqrt, tan, tanh, setcookie, preg_quote, addslashes, bin2hex, count_chars, html_entity_decode, htmlentities, htmlspecialchars_decode, levenshtein, ltrim, nl2br, nl2br, ord, parse_str, rtrim, soundex, str_ireplace, str_replace, str_replace, str_rot13, str_split, strcasecmp, strip_tags, stripos, stripslashes, stristr, strlen, strnatcmp, strncasecmp, strpbrk, strpos, strrev, strripos, strrpos, strstr, strtolower, strtoupper, substr, substr_count, trim, ucfirst, ucwords, base64_decode, empty, empty, is_array, is_bool, isset, utf8_decode, utf8_encode, utf8_encode
spacemedalMichael White (link) for contributing to:
 array_count_values, get_included_files, include, include_once, require, require_once, md5, number_format, parse_str, printf, sha1, sprintf, str_pad, strnatcmp, vprintf, http_build_query, floatval, is_object, print_r
spacemedalWaldo Malqui Silva for contributing to:
 array_fill, array_pad, array_product, array_rand, compact, count, range, abs, defined, ip2long, long2ip, implode, strcmp, strncmp, ucwords, settype
spacemedalPaulo Ricardo F. Santos for contributing to:
 getdate, microtime, constant, define, chop, chunk_split, quotemeta, sprintf, get_headers, gettype, is_double, is_float, is_integer, is_long, is_scalar
spacemedalJack for contributing to:
 compact, max, min, count_chars, htmlentities, md5, parse_str, soundex, sprintf, str_ireplace, strnatcmp, trim, utf8_encode
spacemedalJonas Raoni Soares Silva (link) for contributing to:
 shuffle, abs, setcookie, number_format, number_format, soundex, str_repeat, str_replace, str_rot13, ucwords, wordwrap, wordwrap
spacemedalPhilip Peterson for contributing to:
 sizeof, log10, round, exit, echo, get_html_translation_table, nl2br, str_replace, strchr, urldecode, urlencode, var_export
spacemedalAtes Goral (link) for contributing to:
 array_change_key_case, array_count_values, array_diff_key, each, get_class, preg_quote, addslashes, count_chars, str_rot13, stripslashes
spacemedalLegaev Andrey for contributing to:
 end, reset, file, file_get_contents, function_exists, include, include_once, http_build_query, is_array, is_object
spacemedalMartijn Wieringa for contributing to:
 array_shift, array_unshift, str_ireplace, str_split, strcasecmp, stripos, strnatcmp, substr
spacemedalNate for contributing to:
 array_merge, array_sum, array_unique, pathinfo, addslashes, echo, strncasecmp
spacemedalEnrique Gonzalez for contributing to:
 file_exists, filesize, decbin, decoct, deg2rad, rad2deg
spacemedalPhilippe Baumann for contributing to:
 base_convert, bindec, dechex, hexdec, octdec, empty
spacemedalTheriault for contributing to:
 array_multisort, quoted_printable_decode, quoted_printable_decode, quoted_printable_encode, quoted_printable_encode
spacemedalWebtoolkit.info (link) for contributing to:
 crc32, md5, sha1, utf8_decode, utf8_encode
 
spacemedalAsh Searle (link) for contributing to:
 basename, printf, sprintf, vprintf
spacemedalCarlos R. L. Rodrigues (link) for contributing to:
 array_chunk, array_unique, date, levenshtein
spacemedalJani Hartikainen for contributing to:
 file, file_exists, file_get_contents, filesize
spacemedalOle Vrijenhoek for contributing to:
 convert_uuencode, convert_uuencode, quoted_printable_decode, str_word_count
spacemedaltravc for contributing to:
 rawurldecode, rawurlencode, urldecode, urlencode
spacemedalAlex for contributing to:
 get_html_translation_table, strip_tags, is_int
spacemedalAndrea Giammarchi (link) for contributing to:
 array_map, define, levenshtein
spacemedalErkekjetter for contributing to:
 ltrim, rtrim, trim
spacemedalGeekFG (link) for contributing to:
 krsort, ksort, time
spacemedalJohnny Mast (link) for contributing to:
 array_walk, array_walk_recursive, create_function
spacemedalMichael Grier for contributing to:
 array_unique, wordwrap, rawurlencode
spacemedald3x for contributing to:
 array, explode, unserialize
spacemedalmarrtins for contributing to:
 array_change_key_case, addslashes, stripslashes
spacemedalstag019 for contributing to:
 parse_str, parse_str, http_build_query
spacemedalAJ for contributing to:
 urldecode, urlencode
spacemedalAlfonso Jimenez (link) for contributing to:
 array_reduce, strpbrk
spacemedalAman Gupta for contributing to:
 base64_decode, utf8_decode
spacemedalArpad Ray (mailto:arpad@php.net) for contributing to:
 serialize, unserialize
spacemedalBreaking Par Consulting Inc (link) for contributing to:
 gettimeofday, localtime
spacemedalCaio Ariede (link) for contributing to:
 strtotime, strtotime
spacemedalDavid for contributing to:
 strtotime, is_numeric
spacemedalJosh Fraser (link) for contributing to:
 gettimeofday, localtime
spacemedalKELAN for contributing to:
 get_html_translation_table, gettype
spacemedalKarol Kowalski for contributing to:
 array_reverse, abs
spacemedalLars Fischer for contributing to:
 urldecode, urlencode
spacemedalMarc Palau for contributing to:
 mktime, strip_tags
spacemedalMirek Slugen for contributing to:
 htmlspecialchars, htmlspecialchars_decode
spacemedalOleg Eremeev for contributing to:
 str_replace, str_replace
spacemedalPellentesque Malesuada for contributing to:
 base64_decode, base64_encode
spacemedalPublic Domain (link) for contributing to:
 json_decode, json_encode
spacemedalSakimori for contributing to:
 strlen, wordwrap
spacemedalSteve Hilder for contributing to:
 strcmp, strncmp
spacemedalSteven Levithan (link) for contributing to:
 trim, parse_url
spacemedalThunder.m for contributing to:
 base64_decode, base64_encode
spacemedalTyler Akins (link) for contributing to:
 base64_decode, base64_encode
spacemedalgettimeofday for contributing to:
 date, idate
spacemedalgorthaur for contributing to:
 strcmp, strncmp
spacemedalmdsjack (link) for contributing to:
 include, trim
spacemedal0m3r for contributing to:
 array_diff_assoc
spacemedalAlexander Ermolaev (link) for contributing to:
 trim
spacemedalAllan Jensen (link) for contributing to:
 number_format
spacemedalAndreas for contributing to:
 setcookie
spacemedalAndrej Pavlovic for contributing to:
 serialize
spacemedalAnton Ongson for contributing to:
 str_replace
spacemedalArno for contributing to:
 htmlspecialchars
spacemedalAtli Þór for contributing to:
 nl2br
spacemedalBayron Guevara for contributing to:
 base64_encode
spacemedalBen Bryan for contributing to:
 print_r
spacemedalBenjamin Lupton for contributing to:
 number_format
spacemedalBlues (link) for contributing to:
 strftime
spacemedalBlues at link for contributing to:
 setlocale
spacemedalBobby Drake for contributing to:
 strip_tags
spacemedalBrad Touesnard for contributing to:
 date
spacemedalBryan Elliott for contributing to:
 date
spacemedalCagri Ekin for contributing to:
 parse_str
spacemedalChaosNo1 for contributing to:
 timezone_abbreviations_list
spacemedalChristian Doebler for contributing to:
 sleep
spacemedalCord for contributing to:
 is_array
spacemedalDaniel Esteban for contributing to:
 strpos
spacemedalDavid James for contributing to:
 get_class
spacemedalDavid Randall for contributing to:
 date
spacemedalDer Simon (link) for contributing to:
 echo
spacemedalDino for contributing to:
 serialize
spacemedalDiogo Resende for contributing to:
 number_format
spacemedalDouglas Crockford (link) for contributing to:
 gettype
spacemedalDxGx for contributing to:
 trim
spacemedalEric Nagel for contributing to:
 strip_tags
spacemedalEugene Bulkin (link) for contributing to:
 echo
spacemedalFGFEmperor for contributing to:
 mktime
spacemedalFelix Geisendoerfer (link) for contributing to:
 array_key_exists
spacemedalFrancesco for contributing to:
 empty
spacemedalFrancois for contributing to:
 htmlspecialchars_decode
spacemedalFremyCompany for contributing to:
 isset
spacemedalGabriel Paderni for contributing to:
 str_replace
spacemedalGaragoth for contributing to:
 serialize
spacemedalGilbert for contributing to:
 array_sum
spacemedalHoward Yeend for contributing to:
 number_format
spacemedalHyam Singer (link) for contributing to:
 exit
spacemedalJ A R for contributing to:
 end
spacemedalJalal Berrami for contributing to:
 import_request_variables
spacemedalKirk Strobeck for contributing to:
 strlen
spacemedalKristof Coomans (SCK-CEN (Belgian Nucleair Research Centre)) for contributing to:
 strnatcasecmp
spacemedalLH for contributing to:
 empty
spacemedalLeslie Hoare for contributing to:
 rand
spacemedalLincoln Ramsay for contributing to:
 basename
spacemedalLinuxworld for contributing to:
 bin2hex
spacemedalLuke Godfrey for contributing to:
 strip_tags
spacemedalLuke Smith (link) for contributing to:
 number_format
spacemedalManish for contributing to:
 is_array
spacemedalMarc Jansen for contributing to:
 empty
spacemedalMarco for contributing to:
 get_html_translation_table
spacemedalMartin Pool for contributing to:
 strnatcasecmp
spacemedalMateusz "loonquawl" Zalega for contributing to:
 htmlspecialchars_decode
spacemedalMatt Bradley for contributing to:
 is_int
spacemedalMeEtc (link) for contributing to:
 date
spacemedalMick@el for contributing to:
 stripslashes
spacemedalNathan for contributing to:
 htmlspecialchars
spacemedalNick Callen for contributing to:
 wordwrap
spacemedalNorman "zEh" Fuchs for contributing to:
 utf8_decode
spacemedalOle Vrijenhoek (link) for contributing to:
 filemtime
spacemedalOzh for contributing to:
 dirname
spacemedalPaul for contributing to:
 exit
spacemedalPedro Tainha (link) for contributing to:
 unserialize
spacemedalPeter-Paul Koch (link) for contributing to:
 date
spacemedalPierre-Luc Paour for contributing to:
 strnatcasecmp
spacemedalPul for contributing to:
 strip_tags
spacemedalPyerre for contributing to:
 checkdate
spacemedalReverseSyntax for contributing to:
 htmlspecialchars_decode
spacemedalRival for contributing to:
 number_format
spacemedalRobin for contributing to:
 is_nan
spacemedalSanjoy Roy for contributing to:
 array_diff
spacemedalSaulo Vallory for contributing to:
 strncasecmp
spacemedalScott Cariss for contributing to:
 htmlspecialchars_decode
spacemedalSimon Willison (link) for contributing to:
 str_replace
spacemedalSlawomir Kaniecki for contributing to:
 htmlspecialchars_decode
spacemedalSoren Hansen for contributing to:
 count
spacemedalSteve Clay for contributing to:
 function_exists
spacemedalSubhasis Deb for contributing to:
 array_merge_recursive
spacemedalT. Wild for contributing to:
 filesize
spacemedalT.Wild for contributing to:
 substr
spacemedalT0bsn for contributing to:
 crc32
spacemedalThiago Mata (link) for contributing to:
 call_user_func_array
spacemedalTim Wiel for contributing to:
 date
spacemedalTim de Koning for contributing to:
 is_numeric
spacemedalTod Gentille for contributing to:
 log10
spacemedalValentina De Rosa for contributing to:
 strspn
spacemedalVictor for contributing to:
 ip2long
spacemedalWagner B. Soares for contributing to:
 strtotime
spacemedalXoraX (link) for contributing to:
 dirname
spacemedalYUI Library: link for contributing to:
 setlocale
spacemedalYannoo for contributing to:
 mktime
spacemedalYves Sucaet for contributing to:
 utf8_encode
spacemedalbaris ozdil for contributing to:
 mktime
spacemedalbooeyOH for contributing to:
 preg_quote
spacemedalclass_exists for contributing to:
 get_declared_classes
spacemedaldate for contributing to:
 idate
spacemedaldjmix for contributing to:
 basename
spacemedaldptr1988 for contributing to:
 unserialize
spacemedalduncan for contributing to:
 array_unique
spacemedalecho is bad for contributing to:
 echo
spacemedalejsanders for contributing to:
 vsprintf
spacemedalgabriel paderni for contributing to:
 mktime
spacemedalger for contributing to:
 html_entity_decode
spacemedalhitwork for contributing to:
 utf8_decode
spacemedaljakes for contributing to:
 mktime
spacemedaljohn (link) for contributing to:
 html_entity_decode
spacemedaljohnrembo for contributing to:
 var_export
spacemedalkenneth for contributing to:
 explode
spacemedalmadipta for contributing to:
 get_html_translation_table
spacemedalmarc andreu for contributing to:
 html_entity_decode
spacemedalmetjay for contributing to:
 time
spacemedalmk.keck for contributing to:
 realpath
spacemedalmktime for contributing to:
 gmmktime
spacemedalnobbler for contributing to:
 htmlentities
spacemedalnoname for contributing to:
 get_html_translation_table
spacemedalpenutbutterjelly for contributing to:
 str_ireplace
spacemedalrezna for contributing to:
 stripslashes
spacemedalsankai for contributing to:
 array_count_values
spacemedalsetcookie for contributing to:
 setrawcookie
spacemedalsowberry for contributing to:
 utf8_encode
spacemedalstensi for contributing to:
 intval
spacemedalstrcasecmp, strcmp for contributing to:
 substr_compare
spacemedaltaith for contributing to:
 is_numeric
spacemedaluestla for contributing to:
 strtr

Your name here?

Contributing is as easy as adding a comment with better code, or code for a new function.
Any contribution leading to improvement will directly get your name & link here.


Coming Project features

Project features that we are currently working on:

  • Done - Site. A place for php.js of it's own. See: phpjs.org.
  • Done - Compile. Compile your own php.js version, with only the functions you need. Should generate a hash with which you can retrieve latest versions of your php.js combination.
  • Done - Testsuite. A better test-suite that can be ran locally so developers can easily test before commiting. Also the testing itself should be more thorough.
  • Done - Versioning. Individual functions are versioned, but the entire library should be versioned as well.

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tags: programming, php, javascript
category: Programming - Javascript - PHP equivalents
read: 6,603 times

Add Comment

PHP.JS is outgroing this blog and moving to it's own space. Please leave your comment here: http://phpjs.org/functions/function_exists

Comments

#19. Kevin on 30 December 2008

Member avatar: Kevin@ Brett Zamir: Thanks Brett. I've added the functions. I do have the idea they could be standardized & improved a bit though, but I'll leave that up to the 'future us' :) Let those guys handle it.

Seriously though: I think the class_exists example I've made should return true, but it doesn't. That's a good one to start with.

#18. Brett Zamir on 23 December 2008

Gravatar.com: Brett ZamirAdded one last condition which will find if there is a static members on the class to which an object belongs, as well as some example tests for it as well:

myClass2.prototype.instanceMethod = function () {}
myClass2.prototype.mine = 'my member';
var_dump(property_exists(new myClass2, 'mine')); //true
var_dump(property_exists(new myClass2, 'xpto')); //true, as of PHP 5.3.0
var_dump(property_exists(new myClass2, 'bar')); //false
var_dump(property_exists(new myClass2, 'staticProp')); //true, as of PHP 5.3.0
var_dump(property_exists(new myClass2, 'staticMethod')); //false
var_dump(property_exists(new myClass2, 'instanceMethod')); //false
var myclass2 = new myClass2();
myclass2.staticMethod(); // doesn't exist


function property_exists (cls, prop) {
cls = (typeof cls === 'string') ? window[cls] : cls;
if (typeof cls === 'function' && cls.toSource && cls.toSource().match(new RegExp('this\\.'+prop+'\\s'))) { // Hackish and non-standard but can probably detect if setting the property (we don't want to test by instantiating as that may have side-effects)
return true;
}
return (cls[prop] !== undefined && typeof cls[prop] !== 'function') || (cls.prototype !== undefined && cls.prototype[prop] !== undefined && typeof cls.prototype[prop] !== 'function') || cls.constructor && cls.constructor[prop] !== undefined && typeof cls.constructor[prop] !== 'function';
}

#17. Brett Zamir on 23 December 2008

Gravatar.com: Brett ZamirAnd here's one for property_exists(), based on PHP doc examples:

var myClass = {
mine : {},
xpto : {},
test : function () {
var_dump(property_exists('myClass', 'xpto')); // true
}
}
var_dump(property_exists('myClass', 'mine')); //true
var_dump(property_exists('myClass', 'xpto')); //true
var_dump(property_exists('myClass', 'bar')); //false
var_dump(property_exists('myClass', 'test')); // false (PHP considers methods as distinct from properties)
myClass.test(); // true
 
 
function myClass2 () {
this.xpto = 'something';
}
myClass2.staticProp = 'staticValue';
myClass2.staticMethod = function () {
var_dump(property_exists('myClass2', 'xpto')); // true
}
myClass2.prototype.instanceMethod = function () {}
myClass2.prototype.mine = 'my member';
 
var_dump(property_exists('myClass2', 'mine')); //true
var_dump(property_exists(new myClass2, 'mine')); //true
var_dump(property_exists('myClass2', 'xpto')); //true, as of PHP 5.3.0
var_dump(property_exists('myClass2', 'bar')); //false
var_dump(property_exists('myClass2', 'staticProp')); //true, as of PHP 5.3.0
var_dump(property_exists('myClass2', 'staticMethod')); //false
var_dump(property_exists('myClass2', 'instanceMethod')); //false
myClass2.staticMethod(); // true
 
 
function property_exists (cls, prop) {
cls = (typeof cls === 'string') ? window[cls] : cls;
if (typeof cls === 'function' && cls.toSource && cls.toSource().match(new RegExp('this\\.'+prop+'\\s'))) { // Hackish and non-standard but can probably detect if setting the property (we don't want to test by instantiating as that may have side-effects)
return true;
}
return (cls[prop] !== undefined && typeof cls[prop] !== 'function') || (cls.prototype !== undefined && cls.prototype[prop] !== undefined && typeof cls.prototype[prop] !== 'function');
}

#16. Brett Zamir on 23 December 2008

Gravatar.com: Brett ZamirHere's a slightly hackish and partially non-standard way to get class_exists(). Of course, any function can be instantiated in JavaScript, but I've attempted to do a hopefully more sophisticated checking to see whether it was designed as one.

function A (z) {this.z=z}
alert(class_exists('A')); // true (constructor sets 'this')
var a = new A('str');
alert(class_exists('a')); // false (objects not classes)
 
function B () {}
B.c = function () {}; // Add a static method, making it a class
alert(class_exists('B')); // true
 
function C () {}
C.prototype.z = function () {};
alert(class_exists('C')); // true
 
function D (b) {}
alert(class_exists('D')); // false (seems like a regular function)
 
var e = {
E : function (z) {this.z=z;}
}
alert(class_exists('e.E')); // false (the 'this' refers to containing object, not to an instance property)
 
 
function class_exists (cls) {
cls = window[cls]; // Note: will prevent inner classes
if (typeof cls !== 'function') {return false;}
for (var i in cls.prototype) {
return true;
}
for (var i in cls) { // If static members exist, then consider a "class"
if (i !== 'prototype') {
return true;
}
}
if (cls.toSource && cls.toSource().match(/this\./)) { // Hackish and non-standard but can probably detect if setting a property (we don't want to test by instantiating as that may have side-effects)
return true;
}
return false;
}

#15. Brett Zamir on 23 December 2008

Gravatar.com: Brett ZamirFixing an error and adding more examples:

function Directory () {}
Directory.test = function () {}
Directory.prototype.read = function () {}
$directory = new Directory('.');
alert(true === method_exists($directory,'read')); // true
alert(true === method_exists($directory,'write')); // false
alert(true === method_exists('Directory','test')); // true
alert(true === method_exists('Directory','read')); // false
alert(true === method_exists($directory,'test')); // false
 
function method_exists (obj, method) {
if (typeof obj === 'string') {
return window[obj] && typeof window[obj][method] === 'function'
}
return typeof obj[method] === 'function';
}

#14. Brett Zamir on 20 December 2008

Gravatar.com: Brett ZamirSorry, neglected to see a string was allowable to test for a static method:

function Directory () {}
Directory.test = function () {}
Directory.prototype.read = function () {}
$directory = new Directory('.');
alert(true === method_exists($directory,'read')); // true
alert(true === method_exists($directory,'write')); // false
alert(true === method_exists('Directory','test')); // true


function method_exists (obj, method) {
if (typeof obj === 'string') {
return typeof window[obj][method] === 'function'
}
return typeof obj[method] === 'function';
}

#13. Brett Zamir on 20 December 2008

Gravatar.com: Brett ZamirHere's another one more related to the function here...

Sample based on PHP manual...

function Directory () {}
Directory.prototype.read = function () {}
$directory = new Directory('.');
alert(true === method_exists($directory,'read')); // true
alert(true === method_exists($directory,'write')); // false



function method_exists (obj, method) {
return typeof obj[method] === 'function';
}

#12. Kevin on 17 December 2008

Member avatar: Kevin@ Brett Zamir: get_defined_functions... I must say, sometimes I'm really surprised what you guys come up with :) But it works! I have even hacked a testcase around it. Thanks again.

#11. Brett Zamir on 17 December 2008

Gravatar.com: Brett ZamirHere's one more...

function get_defined_functions() {
var arr = [];
for (var i in window) {
try {
if (typeof window[i] === 'function') {
arr.push(window[i].name);
}
}
catch (e) {
}
}
return arr;
}
alert(get_defined_functions());

#10. Kevin on 15 January 2008

Member avatar: Kevin@ Andrea Giammarchi: Wow you did some impressive work that I was unaware of. Cool :) I will look into the define function later today and add it here, thanks a lot for that.

About the PHP vs JS stuff.. I'm not trying to port or emulate the entire language or control structures of PHP. Indeed I don't see the need because (and this is quite a statement), Javascript seems to have more elegant features in that category anyway.

However in my eyes, PHP does provide a large set of standard functions that make developing very easy, and some of them don't have good standard Javascript implementations, though they often would be great to have client-side.
... [more]
So in this project by also providing the functions separately, I hope to keep people from inventing the wheel and give them a head start.

Thanks for your comment Andrea, well appreciated. And respect for your Overbyte editor & JHP environment. The idea is very interesting, and I can see it's all coded with very high skill.

#9. Andrea Giammarchi on 14 January 2008

Default avatar:Andrea GiammarchiIf you are interested in some similar stuff, looks for JHP setting in overbyte editor.

Finally, You could use my define function too, that accept only scalar values as PHP and is compatible with IE, FireFox, Safari and Opera (Opera devs will fix soon their const keyword ... I guess ...)

http://webreflection.blogspot.com/2007/10/cow-javascript-define-php-like-function.html
... [more]
However, nice stuff .. not so useful in my mind because of different languages nature (I would like to have JS behaviours in PHP, for example :D) but good luck for the project

#8. Legaev Andrey on 08 January 2008

Default avatar:Legaev Andrey@ Kevin: I'm sorry. Not necessary to enlist my email. I did not think about spammers :)

#7. Kevin on 07 January 2008

Member avatar: Kevin@ Legaev Andrey: Hi, I've updated the function and changed your name. I wasn't sure you really want me to enlist your email address?

#6. Legaev Andrey (aka Andrey) on 07 January 2008

Default avatar:Legaev Andrey (aka Andrey)Sorry for my short previous comment and my bad English. Below full version.

If we pass function_name as String then all ok. But if we pass the link to function (link to Object-function) then
this function returns false. In my opinion in this case this function should return true when first
parameter is instance of Function.
... [more]
function function_exists_new( function_name ) {
if (typeof function_name == \'string\')
return (typeof window[function_name] == \'function\');
else
return (function_name instanceof Function);
}

P.S. Please, change my name to Legaev Andrey <legaev_andrey@mail.ru>. Thanks.

#5. Kevin on 06 January 2008

Member avatar: Kevin@ Cord: Thanks for noticing. Fixed!

#4. Cord on 06 January 2008

Default avatar:Cord>>function is_array() {
should be
>>function is_array(a) {

#3. Kevin on 04 January 2008

Member avatar: Kevin@ Steve Clay & Andrey: Thanks You guys I've updated the function. I left the old code in the comments for future reference.

#2. Andrey on 04 January 2008

Default avatar:Andrey>return (typeof window[function_name] == 'function');

Object-function may be defined as not a member of Window object.

#1. Steve Clay on 04 January 2008

Default avatar:Steve Clayreturn (typeof window[function_name] == 'function');