jQuery noConflict IE问题

Question

I'm building a widget that depends on jquery being loaded - I'm using the following to load it and my code:

(function () {

    var jqueryVersion = (window.jQuery !== undefined) ? window.jQuery.fn.jquery.charAt(0) + window.jQuery.fn.jquery.charAt(2) : 0;

    var jQuery;
    /******** Called once jQuery has loaded ******/
    function scriptLoadHandler() {
        jQuery = window.jQuery.noConflict(true);
        main();
    }

    /******** Load jQuery if not present *********/
    if (parseInt(jqueryVersion) < 17) {
        var script_tag = document.createElement('script');
        script_tag.setAttribute("type", "text/javascript");
        script_tag.setAttribute("src", "//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js");
        script_tag.onload = scriptLoadHandler;
        script_tag.onreadystatechange = function () { // Same thing but for IE
            if (this.readyState === 'complete' || this.readyState === 'loaded') { scriptLoadHandler(); }
        };
        document.getElementsByTagName("head")[0].appendChild(script_tag);
    } else {
        jQuery = window.jQuery;
        main();
    }

    function main() {
        //my code goes in here
        //leaving blank for now because I still get error
    }

})();

I got most of that from here: http://alexmarandon.com/articles/web_widget_jquery/

I need jquery 1.7 or higher because I use the .on() method. When I run this on a page using jquery that is older than 1.7 I sometimes get errors in IE that lead me to believe there is a conflict with either the old version of jquery or some other js on the page. Some errors:

SCRIPT5007: Unable to get property 'forceInt' of undefined or null reference

SCRIPT5007: Object expected

SCRIPT5007: Unable to get property 'easing' of undefined or null reference

SCRIPT438: Object doesn't support property or method 'on'

These errors go away if I change

jQuery = window.jQuery.noConflict(true);

to

jQuery = window.jQuery.noConflict();

Am I doing something wrong?

Answer 1

Your problem might be caused by the fact that the 'handler' is called twice.

http://msdn.microsoft.com/en-us/library/ie/hh180173(v=vs.85).aspx

Also, taken from http://api.jquery.com/jQuery.noConflict/

"If necessary, you can free up the jQuery name as well by passing true as an argument to the method. This is rarely necessary, and if you must do this (for example, if you need to use multiple versions of the jQuery library on the same page), you need to consider that most plug-ins rely on the presence of the jQuery variable and may not operate correctly in this situation."