SharePoint 2010 Server. I edited section of my masterpage like this(in sharepoint designer, not programmatically):

    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> 

But how can I ensure that I don't connect jQuery twice? Something like this

    <script>if (typeof jQuery == 'undefined') { 
    // jQuery is not loaded} 
    else {
    // jQuery is loaded

but how can I dynamically load jQuery from here? Or if I edit .masterpage, I should look by myself if there is no jQuery already added?

  • Why can't you just open the master page and remove any duplicate references? Jan 1, 2015 at 19:33
  • ufff) I thought there is an easy way.. Thank You for response!)
    – Gennady G
    Jan 1, 2015 at 19:50

2 Answers 2


Here is script you can use to dynamically load jQuery if it not present.

// Only do anything if jQuery isn't defined
if (typeof jQuery == 'undefined') {
    if (typeof $ == 'function') {
        // warning, global var
        thisPageUsingOtherJSLibrary = true;
    function getScript(url, success) {
        var script = document.createElement('script');
        script.src = url;
        var head = document.getElementsByTagName('head')[0],done = false;
        // Attach handlers for all browsers
        script.onload = script.onreadystatechange = function() {
            if (!done && (!this.readyState || this.readyState == 'loaded' || this.readyState == 'complete')) {
                done = true;                    
                // callback function provided as param
                script.onload = script.onreadystatechange = null;
    getScript('http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js', function() {       
        if (typeof jQuery=='undefined') {           
            // Super failsafe - still somehow failed...         
        } else {            
            // jQuery loaded! Make sure to use .noConflict just in case
            if (thisPageUsingOtherJSLibrary) {
                // Run your jQuery Code
            } else {
                // Use .noConflict(), then run your jQuery Code
} else { // jQuery was already loaded       
    // Run your jQuery Code



The follwoing code will try to load JQuery from Google CDN. If it fails, then it will look for a local copy of JQuery:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js">
window.jQuery || document.write('<script src="/_layouts/15/JQuery/jquery-1.7.1.min.js" type="text/javascript"></script>');

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