Auto include javascript file if not already included

Question

I have an external javascript file that relies on the presence of another file.

How can I, using JavaScript (or jQuery) automatically include this file if it is not already included (I can test based on the presence of a known function in this external file)

Edit: It now includes the file but writes over everything completey! I have tried all suggested methods put forward so far

Salman Arshad · Accepted Answer · 2010-05-21 14:05:41Z

12

Well if that JavaScript file defines a specific variable (or a function) you can check its presence by checking typeof that_variable, then load the JavaScript file if necessary. An example, here is how you load swfobject library if its not available on the page:

if (typeof swfobject == "undefined") {
   var e = document.createElement("script");
   e.src = "http://ajax.googleapis.com/ajax/libs/swfobject/2/swfobject.js";
   e.type = "text/javascript";
   document.getElementsByTagName("head")[0].appendChild(e); 
}

edited May 21, 2010 at 14:05

answered May 21, 2010 at 13:59

Salman Arshad

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2 Comments

Alex K Over a year ago

Just a note... I tried this in jQuery's document ready function and then tried calling the function in my file and it was still undefined. Ended up doing it a different way.

Salman Arshad Over a year ago

@RegionalC: you must call that function after the dynamically loaded script is loaded. On most browsers, you can assign an onload event to dynamically generated script elements (e.onload = function() {}). You can call your function from within that event handler. On (stupid) IE 6/7/8 you can use onreadystatechange event.

Chris · Accepted Answer · 2010-05-21 09:39:08Z

1

http://www.cryer.co.uk/resources/javascript/script17_include_js_from_js.htm

answered May 21, 2010 at 9:39

Chris

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