jQuery .prop() compatibility

Question

I'm trying to test if the .prop() method exists on the current jQuery included (for compatibility reason) via:

if(typeof $.prop === 'function')

I would expect that the condition above is true for jQuery >= 1.6 and false for jQuery < 1.6 as I can understand from the docs

Anyway, testing this on jsfiddle, leads to:

typeof $.prop === 'function' is:

• true when jQuery >= 1.6
• false when jQuery < 1.6 and jQuery > 1.3
• true when jQuery <= 1.3

here is the very very simple script which provide the results above (just switch jQuery version to see what I've described).

When I try to use that .prop() with jQuery i.e. 1.3 I get the .prop is not a function error. The same problem occours also testing outside jsfiddle. Is it normal such a behavior? How could I truly test if .prop() is available?

Thanks

Answer 1

alert(typeof $.fn.prop === 'function')

You want to check for the .prop method on the jQuery prototype which lives on $.fn. This is false in 1.3.

Also I would avoid feature detection for jQuery versions and instead support a particular version (and up).

Answer 2

What I did, is build a compatible function for prop, for jQuery versions, which doesn't use prop:

(function($){
    if (typeof $.fn.prop !== 'function')
    $.fn.prop = function(name, value){
        if (typeof value === 'undefined') {
            return this.attr(name);
        } else {
            return this.attr(name, value);
        }
    };
})(jQuery);

You can test this code: http://jsfiddle.net/JtK2Q

Answer 3

You're checking for the existence of a static method.

You need to check for the instance method by writing $.fn.prop ($.fn is the same as $.prototype).