title: Passing a select value to a link URL parameter
body: <p>I have a <code>Buy</code> button that a user can click on to purchase a particular product.<br>
  This takes them through to a purchase form I've built.<br>
  One of the fields on that form uses a URL parameter so it knows which product the user wants to buy.</p>
  
  <p>So what I want to do is to have a HTML select field somewhere on the page before (where the <code>Buy</code> button is) and allow the user to select the product there.<br>
  Then when they click on the <code>Buy</code> button, it passes the selected value through via the URL. For example:</p>
  
  <pre><code>// Some content here promoting the three products.
  
  // Now I want a select field for the user to choose one of the three products, like this.
  
  &lt;select id="productSelect"&gt;
      &lt;option value="product1"&gt;Product 1&lt;/option&gt;
      &lt;option value="product2"&gt;Product 2&lt;/option&gt;
      &lt;option value="product3"&gt;Product 3&lt;/option&gt;
  &lt;/select&gt;
  
  // Then I have some more content here showing the pros/cons of each product.
  
  // Finally, I have a buy button at the bottom of the page that takes them to the page with the purchase form. 
  // Here is where I want to grab the value of the select field and pass it through via the "product" parameter like this.
  
  &lt;a class="button" href="/buy/?product='select value here'"&gt;Buy&lt;/a&gt;
  </code></pre>