I have created a view for an action window. I want to execute it from a custom button from javascript.

I read about how to use Javascript in odoo, but I am not clear enough. Besides, I need to add that javascript function on a custom button in the Employees' sheet to open the action window.

The action view contains a button as well, and I need to execute a python method and in turn, add another HTML element to the view (In this case an <img/> tag) clicking to that button.

Do I need to create a QWeb template inside the group tag where the image will be located?

How can I do all this using the only javascript?

Action view code:

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
    <data>
        <template id="assets_backend" name="static_resources assets" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/mymodel/static/src/js/load_captcha.js"/>
            </xpath>
        </template>

        <record id="captcha_view" model="ir.ui.view">
            <field name="name">captcha.view</field>
            <field name="model">captcha.window</field>
            <field name="arch" type="xml">
                <form>
                    <group name="group_top">
                        <group name="group_left">
                            <field name="captcha_code"/>
                            <button name="load_captcha" string="Cargar código"
                                   type="object" class="oe_highlight load_captcha" icon="fa-refresh"/>
                        </group>
                        <group name="group_right">
                            <!-- Here I want to appear the image when I click the button above -->
                        </group>
                    </group>
                    <footer>
                        <button name="main" string="Actualizar" type="object" class="oe_highlight"/>
                    </footer>
                </form>
            </field>
        </record>
    </data>
</odoo>