how to add js functions to functions.php

Hello. I have put an ajax query in the functions.php file like this.

add_action(‘wp_footer’, ‘my_ajax_code’);
function my_ajax_code() {
?>
<script type=”text/javascript”>
function login(){
alert(“fgffg”);
var emailaddress = document.getElementById(“emailaddresstext”).value;
var password = document.getElementById(“passwordtext”).value;

$.ajax({
type: “POST”,
url: “https://www.mysite.ca/wordpress/wp-admin/login.php&#8221;,
data: “emailaddress=”+emailaddress+”&password=”+password,
success: function(html){

alert(“working “+html);

if(html==’true’) {
$(“#add_err”).html(“Right email address or password”);

}
else {
$(“#add_err”).css(‘display’, ‘inline’, ‘important’);
$(“#add_err”).html(“<img src=’images/alert.png’ />Wrong email address or password”);
}
},
beforeSend:function()
{
$(“#add_err”).css(‘display’, ‘inline’, ‘important’);
$(“#add_err”).html(“<img src=’images/ajax-loader.gif’ /> Loading…”)
}
});

return false;

}
add_action( ‘wp_enqueue_scripts’, ‘login’ );

</script>
<?php
}

I was taught to do this by someone. I was using

jQuery(document).ready(function($) {

});
It wasn’t working in the footer.php file, so I put my code in the functions.php file and now it works. But now if i want to use my login(){} function anywhere on my site it doesnt work. How do i make that js function work on the rest of my site? thanks