Customize the login screen text

gistfile1.php

<?php
/**
 * Customize the login screen text
 *
 * Some sites, primarily membership sites, are setup where the usernames ARE their email address.
 * This is great, but the login screen can confuse users. So help with the confusion, we remove
 * all references of "Username" on the login screen and replace with "Email".
 *
 * @since 1.0.0
 */
function ja_custom_login_text() { 
	?>
	<script type="text/javascript">
	jQuery(document).ready(function($) {
		$("label[for='user_login']").html(function(index, text) {
			return text.replace("Username or E-mail", "Email Address");
		});
		$("label[for='user_login']").html(function(index, text) {
			return text.replace("Username", "Email Address");
		});
		$("p.message").html(function(index, text) {
			return text.replace("username or email address", "email address");
		});
		$("div#login_error").html(function(index, text) {
			return text.replace("Invalid username", "Invalid email address");
		});	
	});
	</script>
	<?php
}
add_action( 'login_head', 'ja_custom_login_text', 20 );