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Tuesday, April 17, 2012
How to detect what Library is behind the $ function?
I am developing some JavaScript that should work with either Prototype.js or JQuery, thus I need some way to identify what is the primary library in use. How can I do that?
Write it without dependency on any library and it should work fine with both jQuery and Prototype ;)
Seriously, isn't one of the main points of these library to avoid having to write three different variations of each line of code for each browser? Writing code to try to suit more than one library seems quite silly.
Anyway, looking at the documentation for either library for about 5 seconds should give you a hint as to what properties jq $ will have that pt $ will not. This suggests that you haven't really bothered to look at the differences between the frameworks (which is obviously going to be the best way to tell them apart, right?). Are you sure you know what you're getting yourself into?
@SLaks and @Chacha102 are right for detecting jQuery, but if you want to make sure that if the $ function is not from jQuery, comes from PrototypeJS, you can:
if (typeof $ == 'function') { if ($.fn && $.fn.jquery) { // $.fn.jquery contains the version number // jquery } else if (window.Prototype && Prototype.Version) { // prototype } }
I am developing some JavaScript that should work with either Prototype.js or JQuery, thus I need some way to identify what is the primary library in use. How can I do that?
Your question is ambiguous, there are two obvious meanings to me so I'll answer both.
If you mean you want write code that will work regardless of whether jQuery or Prototype.js has been used, the answer is that it is quite easy to write code that works regardless of the libraries that have been, or will be, loaded. So there is no need to discover which one has been used.
If you mean that you are going to write two separate scripts, one for jQuery and one for Prototype.js, then, depending on which one you "detect", you'll load one script or the other, then you basing your code on a very bad architecture. Neither of those libraries support a particularly wide selection of browsers and both need updating whenever a new version comes out, even of the "popular" ones they support.
Attempting to support both using separate scripts will create an on-going maintenance headache - times two. Or perhaps that is your intention.
You can check for jQuery like this:
ReplyDeleteif (window.$ === window.jQuery)
Well, you could check for the presence of jQuery:
ReplyDeleteif(window.jQuery !== "undefined")
{
// jQuery Yay!
}
and then if it is assigned to $
if(window.jQuery === window.$)
{
// jQuery Yay!
}
Could jQuery noconflict help? Then you could use jQuery for jQuery and $ for prototype.
ReplyDeleteWrite it without dependency on any library and it should work fine with both jQuery and Prototype ;)
ReplyDeleteSeriously, isn't one of the main points of these library to avoid having to write three different variations of each line of code for each browser? Writing code to try to suit more than one library seems quite silly.
Anyway, looking at the documentation for either library for about 5 seconds should give you a hint as to what properties jq $ will have that pt $ will not. This suggests that you haven't really bothered to look at the differences between the frameworks (which is obviously going to be the best way to tell them apart, right?). Are you sure you know what you're getting yourself into?
As several have mentioned:
var whosThatDollarSign = typeof window.$=='undefined' ? 'none' : (window.$==window.jQuery ? 'jQuery' : 'not jQuery')
@SLaks and @Chacha102 are right for detecting jQuery, but if you want to make sure that if the $ function is not from jQuery, comes from PrototypeJS, you can:
ReplyDeleteif (typeof $ == 'function') {
if ($.fn && $.fn.jquery) { // $.fn.jquery contains the version number
// jquery
} else if (window.Prototype && Prototype.Version) {
// prototype
}
}
I am developing some JavaScript that should work with either Prototype.js or JQuery, thus I need some way to identify what is the primary library in use. How can I do that?
ReplyDeleteYour question is ambiguous, there are two obvious meanings to me so I'll answer both.
If you mean you want write code that will work regardless of whether jQuery or Prototype.js has been used, the answer is that it is quite easy to write code that works regardless of the libraries that have been, or will be, loaded. So there is no need to discover which one has been used.
If you mean that you are going to write two separate scripts, one for jQuery and one for Prototype.js, then, depending on which one you "detect", you'll load one script or the other, then you basing your code on a very bad architecture. Neither of those libraries support a particularly wide selection of browsers and both need updating whenever a new version comes out, even of the "popular" ones they support.
Attempting to support both using separate scripts will create an on-going maintenance headache - times two. Or perhaps that is your intention.
--
Rob