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if jQuery isn't defined, load it
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| // 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 | |
| success(); | |
| script.onload = script.onreadystatechange = null; | |
| head.removeChild(script); | |
| }; | |
| }; | |
| head.appendChild(script); | |
| }; | |
| getScript('http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js', function() { | |
| if (typeof jQuery == 'undefined') { | |
| // Super failsafe - still somehow failed... | |
| } else { | |
| // jQuery loaded! Make sure to use .noConflict just in case | |
| fancyCode(); | |
| if (thisPageUsingOtherJSLibrary) { | |
| // Run your jQuery Code | |
| } else { | |
| // Use .noConflict(), then run your jQuery Code | |
| } | |
| } | |
| }); | |
| } else { // jQuery was already loaded | |
| // Run your jQuery Code | |
| }; |
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this is an async method taken from: https://css-tricks.com/snippets/jquery/load-jquery-only-if-not-present/