How to include jQuery library in single js file wi

Question

3rd party websites can place my script tag on their websites, like so on for example ExternalSite.html in the head section:

<script type="text/javascript">
(function () {
    var ttScript = document.createElement('script'); ttScript.async = true;
    ttScript.src = '//www.example.com/script/myscript.js';
    (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(ttScript);
})();
</script>

On my own server, in the file myscript.js I have this code:

$.ajax({
    url: "http://www.example.com/iplookup.php",
    data: null,
    type: 'GET',
    crossDomain: true,
    dataType: 'jsonp'
}).done(function (json) {
    self.ip = json;
});

But once a user visits the 3rd party site, on the first line here I get Uncaught ReferenceError: $ is not defined

Now this is probably because I don't reference jQuery on the 3rd party site, where I include the myscript.js file. The problem is that:

1. I do not know if this 3rd party site even has jQuery running
2. I don't know how to reference jQuery from myscript.js, also without possibly interfering with an existing jQuery reference on the 3rd party site

Answer 1

First make a check for jQuery load using javaScript

    window.onload = function() {
        if (window.jQuery) {
            // jQuery is loaded  
            // Now insert your scripts        
        } else {
            // jQuery is not loaded
            // Load it manually from any cdn e.g., //ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js        
        }
    }

There are some other similar ways of checking which we can use

    if (typeof jQuery != 'undefined') {
        // jQuery is loaded  
    } else {
        // jQuery is not loaded
    }

    if (jQuery) {
        // jQuery is loaded  
    } else {
        // jQuery is not loaded
    }

There 's a working fiddle available by atornblad which also tells the time jQuery took to load.

You can have a look for a better reference.

Hope this helps..