How to access HTML input values from Twig and vice versa

Question

I am new to Craft and Twig in general. I have encountered the following problems and struggling to find a solution for hours.

1. I want to access the value of "foo" input field inside the twig delimiters to set the "json" variable.
2. I want to change the "clicked" boolean, whenever the submit button is clicked.

The myFunc is a function that I am using from a custom plugin so it is not relative. I have commented what I've last tried and does not work for me.

I am using Craft 3, if that helps.

{% block body %}
    {% set clicked = false %}

    <form name="search" action="{% set clicked = true %}">
        <label for="foo">Foo</label>
        <input name="foo" type="text"/>
        <input type="submit" value="Get Json"/>
        {#    <a href="{{ set clicked = true }}"#}
    </form>

    {% if clicked %}
        {% set json = jsonator_myFunc(search.foo.vars.value) %}
    {% endif %}

{% endblock %}

EDIT/SOLUTION:

A few more days into Craft CMS and chill and I realize how silly my question is.

Thank you for the replies. The solution which I was looking for is:

craft.request.getParam('foo')

Answer 1

You can do it without JavaScript (if you don't mind the page refreshing) by accessing the request variable:

https://docs.craftcms.com/api/v3/craft-web-twig-variables-request.html#public-methods

{{ craft.app.request.getParam('foo') }} {# Should be the value of the input named 'foo' #}

Answer 2

Twig (at least within the context of Craft) doesn't work this way I'm afraid. The Twig template is processed on the server and HTML is returned to the browser.

You're trying to change the Twig based on an event in the Browser, but that at that time, there is no longer Twig, just HTML.

So your solution will need to involve Javascript to change the HTML/DOM rather than the approach you're going for here.