Include js files in Custom WordPress Plugin

Solution:

The right action is wp_enqueue_scripts

 add_action('wp_enqueue_scripts', 'mslb_public_scripts');

 function mslb_public_scripts(){
   wp_register_script('custom_js', plugins_url('/js/public/snappy-wordpress-plugin.js',__FILE__ ), array('jquery'), '', true);
   wp_enqueue_script('custom_js');
 }