How to make connection of javascript with odoo?

For example:- I declared a button in xml and written a function in javascript then how to call that function on xml button.

My code is :-

xml button declaration:-

<footer>
    <button name="button" onclick="updatetxt(fun)" string="ok"/>
</footer>
         
     
     
javascript and xml connection code:-
     
<?xml version="1.0" encoding="utf-8"?> 
<openerp> 
    <data> 
        <template id="assets_backend" name="Javascript_Test" inherit_id="web.assets_backend">
            <xpath expr="." position="inside"> 
                  <!-- <link rel="stylesheet" href="/web/static/lib/bootstrap/css/bootstrap.css"/> -->
                  <!-- <link rel="import" href="//static/src/timesheet.html"/> -->
                  <script type="text/javascript" src="/Javascript_Test/static/src/js/document.js"/>
            </xpath> 
        </template> 
         
    </data> 
</openerp>
    
javascript code:-
    
function updatetxt()
    {
        alert("hello");
    }
     
manifeast file:-
     
'data': [       
        'views/views.xml',
        'views/java_script.xml',
 ],

 'js': [
 'static/src/js/document.js'
],
  
     
So how to declare javascript on button with xml in odoo?