Common Javascript File for all Themes I have a multi-site installation using domain access module and each sub-domain has its own theme. I have a javascript file which is common to all the themes. Right now I've placed the js file inside all the themes folder. Is there a way to place the js file in a common location so that all themes can share it ? Can I use Libraries API module for this purpose ?
Yes, you can use the Libraries API for this.  The docs explain all of this fairly well.   This is best for things that change infrequently.

For my custom Javascript libraries (which I work on continuously), I make module with an instance of hook_library

function mymodule_util_library ()
{
    $path = drupal_get_path("module", "mymodule_util");

    $libraries = array();

    $libraries["mymodule_util"] = array(
        "title" =&gt; "MyModule Javascript Utilities", 
        "version" =&gt; "0.0",
        "js" =&gt; array(
            $path . '/UTIL.js' =&gt; array(),
            $path . '/UTIL.HTML5.js' =&gt; array(),
            $path . '/UTIL.COLOR.js' =&gt; array(),
            $path . '/UTIL.MATH.js' =&gt; array(),
        ),

        'weight' =&gt; -10,
    );

    return $libraries;
}


Put the module in "site/all/modules" so all of your sites can see it, then enable it on the sites you need.

Then, wherever you need these JS libraries, you use drupal_add_library

drupal_add_library("mymodule_util", "mymodule_util", $every_page);


Typically, this is in a hook_block_view or a preprocess function.