How to add call a js file in custom module that are added in libraries folder in drupal 7? I am creating a custom module in drupal 7 and adding a js file in sites/all/libraries folder but its not working.Please check my code 

function mymodule_library(){
$libraries['mymodule'] = array(
    'title' =&gt; 'My custom', 
    'website' =&gt; 'http://www.test.com/test', 
    'version' =&gt; '1.7.14',
    'js' =&gt; array(
      'sites/all/libraries/mymod/custom.js' =&gt; array(),
    ),
);
return $libraries;


}
That code just registers the library with the system. To use it, you need to add it to the page with either

drupal_add_library('mymodule', 'mymodule');


or as part of a render array:

$build['#attached']['library'][] = array('mymodule', 'mymodule');