Put code into body tags near top, using a plugin

How do I use a plugin to put this inside the body of every page on my WP site, for facebook integration. (Yes, I know other plugins can do it, but I want to do it myself.) Facebook recommends as close to the top of the lead body tag as possible.

Thanks!

<script>(function(d, s, id) {
var js, fjs = d.getElementsByTagName(s)[0];
if (d.getElementById(id)) return;
js = d.createElement(s); js.id = id;
js.src = "//connect.facebook.net/en_US/all.js#xfbml=1&appId=99999999999";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));</script>

Solutions Collecting From Web of "Put code into body tags near top, using a plugin"

Put that script into a file somewhere in your theme folder. Include it using the following code in your theme’s functions.php file:

<?php
function wpa_65602_enqueue_scripts() {
     wp_enqueue_script( 'facebook', get_bloginfo( 'template_url' ) . '/path/to/script.js' );
}
add_action( 'wp_enqueue_scripts', 'wpa_65602_enqueue_scripts' );

Ultimately, further research found there is an effort to add wp_body as a hook, but it is not yet implemented. In the meantime, one can append or prepend it to the content of the loop. But in this case, adding the facebook stuff at hook wp_footer works. This is what I’ve done.