How to change the page URL with a button

it should still fix some issue Pretty open question ... One way would be to work with views when showing a node.
In the view you should use a custom php field, which collects the record (nid) within the course-node table. And then create a link using the drupal path_alias function or by using node/nid ...

I wish did fix the issue. I would recommend to provide a public property in your MasterPage that you can use to set/get the Label's Text.
in your Master(assuming it's type is called SiteMaster):

public String ShoppingCartNumber{ 
    get{ return LblShoppingCart.Text; }
    set{ LblShoppingCart.Text = value; }
}

SiteMaster master = (SiteMaster)Page.Master;
master.ShoppingCartNumber = "1234";

hope this fix your issue The reason it's not working is that right now you're overwriting the onclick event in your JavaScript. You start out with an onclick on your input element, then when you set the onclick again in the JavaScript, it overwrites your original onclick that calls toggle().
One way to fix this would be to use event listeners, which support binding multiple functions to onclick, but in your case it will be easier to just add the toggleClass into the onclick you define in your JS, and remove the one you have in your input tag. Here is an example that toggles both header visibility and background color, by using a single onclick function for each:

document.getElementById('showHideContainer').onclick = function () {
    divTest = document.getElementById('header');
    if (divTest.style.display === "none") {
        divTest.style.display = 'block';
    } else {
        divTest.style.display = "none";
    }
    $('body').toggleClass('style2');
};

body {
    background-color:grey;
    z-index:3;
}
body.style2 {
    background-color:white;
    z-index:3;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="header" class="style2">
    <div id="header2" class="style2">Public Vision</div>
</div>
<input id="showHideContainer" type="image" src="http://i.imgur.com/5LGqY2p.jpg?1" height="100" width="100" alt="On" ;>

hope this fix your issue For the functionality you want to do, you need to understand useState and useEffect. useState is very straightforward and useEffect is for the component lifecycle methods.
First rule of thumb for using hooks is you cannot nest that hook into conditions. You have to love hooks unconditionally.

import React, { useEffect, useState } from "react";

const ContactList = (props) => {
    // see how it declares and set the state
    const [contacts, setContacts] = useState([]); 

    useEffect(() => {
        // for all the lifecycle methods, you can use this.
        loadContacts();
        // return a function for the componentWillUnmount
        return;
    }, [])

    const loadContacts = () => {
        const url = `https://student-example-api.herokuapp.com/v1/contacts.json?per=${per}&page=${page}`;
        fetch(url)
            .then(response => response.json())
            .then(json => { 
                // setting state
                setContacts([...contacts, json.contacts]);
            });
    }

    return (
        // whatever you want to render...
    )
}

around this issue I have a cluster of buttons that behave like a toggle. I have this "button group" repeated in various rows inside of a table. I want the user to be able to click on button inside this "button group" and triggered an "active state" (colors it differently) but only of that specific "button group", inside of that specific row , I think this is what you're trying to achieve :

$(document).ready(function() {
   $('.buttongroup-toggle').click(function(a) {
      $(this).siblings().removeClass("btn-active");
      $(this).addClass("btn-active");        
   });
});