Add js into a theme [closed]

Your code should look like this

function my_scripts_styles() {
    wp_register_script('easing', get_template_directory_uri() . '/js/easing.js',  '2014-12-030', true );
    wp_enqueue_script('easing');
}

add_action( 'wp_enqueue_scripts', 'my_scripts_styles' );

The above code should work fine. Also don’t forget to check if you have properly specified the path to your js file.

Check well that you have a functions.php and not function.php file.

Since your $in_footer parameter is set to true check that you do have a footer.php file included in your theme and that the footer.php file includes this line of code:

wp_footer();

Good luck !