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I have various JS libraries in my web application, which are loaded before my main JS file (main.js). One of these libraries is jshashtable, but when I try to create a new Hashtable object in main.js, Google Chrome and Firefox throw a ReferenceError, complaining that the variable does not exist.

Here is the <head> of the application:

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
 <script type="text/javascript" src="/static/jquery-1.4.4.min.js"></script>
 <script type="text/javacsript" src="/static/jshashtable-2.1.js"></script>
 <script type="text/javascript" src="/static/main.js"></script>

Here is the problem line in main.js:

posts = new Hashtable();

This line is inside a function called init which is called when the page has finished loading (using the jquery $(document).ready() function).

Any reason why Hashtable is not global? Google maps and jquery objects work with no such problem. The source of jshashtable can be seen on Google code.

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1 Answer 1

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Updated answer: The problem is that you've got a typo in the script tag:

<script type="text/javacsript" src="/static/jshashtable-2.1.js"></script>
<!--                   ^^---- here (the letters are transposed)       -->

I couldn't understand why you would be running into a problem and decided to actually copy-and-paste your script tags and replicate the structure exactly on my machine. And things stopped working and my world tilted 3° counter-clockwise until I finally stared at them long enough to see it.

Provided that the jshashtable code really is at /static/jshashtable-2.1.js and your server is serving it up correctly (double-check on Chrome's resources tab in the dev tools), I can't see any reason for that. Your scripts are in the right order, and jshashtable's docs show using a global Hashtable (and the code link you gave clearly shows it creating one).

Edit: I've just replicated that same structure (same scripts, same order, using jQuery(document).ready(function() { ... });) on my own server, and am not having that problem. I can create a Hashtable and use its functions.

My HTML:

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-type" content="text/html;charset=UTF-8">
<title>Test Page</title>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script type='text/javascript' src='jquery-1.4.4.js'></script>
<script type='text/javascript' src='jshashtable-2.1.js'></script>
<script type='text/javascript' src='main.js'></script>
</head>
<body>
</body>
</html>

My main.js:

jQuery(document).ready(function() {
    try {
        var ht = new Hashtable();
        display("typeof ht = " + typeof ht);
        display("ht.size() = " + ht.size());
    }
    catch (e) {
        display("Exception: " + e);
    }

    function display(msg)
    {
        $("<p>").html(msg).appendTo(document.body);
    }
});

Only difference is I'm not using a /static prefix, and I'm absolutely certain that makes no difference.

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9 Comments

I have verified that the jshashtable script is loading properly; the code shows up in dev tools with no errors.
@James: Very strange. I've replicated the structure (just edited my answer) and am not seeing the behavior you're describing. Unless something is actively clearing Hashtable, I can't see why it happens to you.
@James: Found it. I actually copied and pasted your script tags and things stopped working. Ultimately found the typo. Updated.
Brilliant! Thank you - I thought I was missing something simple.
@James: No worries, we both were. Note to self: If the path looks right, and I even see the script load in Resources, check the type attribute. :-) BTW: You can drop the type entirely. Every browser on the planet defaults to JavaScript, and it's now even the official default as of HTML5. Best,
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