jQuery version compatibility detection

Question

Are there any resources that can test a jQuery script/extension/plugin/whatever for version compatibility issues?

Answer 1

Are you wanting to get the current version of jQuery and test it to see if its a certain version?

$().jquery;

That will get the version.

Metropolis

Answer 2

There are no automated tools for this, at least that I have ever seen. The reasoning for this is the jQuery core team tries to not introduce breaking changes unless there's a real long-term benefit. This means that when there are breaking changes, what you wanted isn't something an automated system can always tell you.

Let's use jQuery 1.4 as an example, here's a list of breaking changes:
http://jquery14.com/day-01/jquery-14#backwards

• jQuery() is now an empty set, good or bad?
• jQuery.browser.version is now browser version, good or bad?
• JSON is now subject to much stricter parsing, good or bad?

Those are just a handful, but whether they break or help your code often depends. Now if you had .attr(val, func()) then obviously this is 1.4+ only, that you could detect...so an engine that could determine the minimum version of jQuery your code could use may be possible.

Checking compatibility issues, which I take to mean breaking changes in most cases, would be much more difficult, because they are (mostly) by nature very odd or corner cases that are broken...otherwise the team wouldn't have broken them :)

Answer 3

Just wrote a small jQuery plugin to help with version compatibility issues... feel free to improve upon it.

(function($) {
    /**
     * Used for version test cases.
     * 
     * @param {string} left A string containing the version that will become
     *        the left hand operand.
     * @param {string} oper The comparison operator to test against. By
     *        default, the "==" operator will be used.
     * @param {string} right A string containing the version that will
     *        become the right hand operand. By default, the current jQuery
     *        version will be used.
     *        
     * @return {boolean} Returns the evaluation of the expression, either
     *         true or false.
     */
    $.isVersion = function(left, oper, right) {
        if (left) {
            var pre = /pre/i,
                replace = /[^\d]+/g,
                oper = oper || "==",
                right = right || $().jquery,
                l = left.replace(replace, ''),
                r = right.replace(replace, ''),
                l_len = l.length, r_len = r.length,
                l_pre = pre.test(left), r_pre = pre.test(right);

            l = (r_len > l_len ? parseInt(l) * ((r_len - l_len) * 10) : parseInt(l));
            r = (l_len > r_len ? parseInt(r) * ((l_len - r_len) * 10) : parseInt(r));

            switch(oper) {
                case "==": {
                    return (true === (l == r && (l_pre == r_pre)));
                }
                case ">=": {
                    return (true === (l >= r && (!l_pre || l_pre == r_pre)));
                }
                case "<=": {
                    return (true === (l <= r && (!r_pre || r_pre == l_pre)));
                }
                case ">": {
                    return (true === (l > r || (l == r && r_pre)));
                }
                case "<": {
                    return (true === (l < r || (l == r && l_pre)));
                }
            }
        }

        return false;
    }
})(jQuery);

Can be used like so:

$.isVersion("1.4.2"); // returns true, if $().jquery == "1.4.2"
$.isVersion("1.3.2", ">"); // returns true if $().jquery > "1.3.2"
$.isVersion("1.3", ">", "1.2.6"); // returns true
$.isVersion("1.3.2", "<", "1.3.1"); // returns false
$.isVersion("1.4.0", ">=", "1.3.2"); // returns true
$.isVersion("1.4.1", "<=", "1.4.1"); // returns true

Also supports pre-releases (releases are weighed heavier than pre-releases, so that 1.4.0pre < 1.4.0):

$.isVersion("1.4.2", "<=", "1.4.2pre"); // returns false