Add Determine Which Button Submitted The Form as an HTML TIL

html/determine-which-button-submitted-the-form.md

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+# Determine Which Button Submitted The Form
+
+It is pretty common for a form to have a singular submit button. If the user
+clicks 'Submit', then the form fires a `POST` off to the server, the server can
+process the request, and that's it.
+
+But what about a form that has two or more buttons? For instance, imagine some
+kind of consent form where the user needs to either _Accept_ or _Reject_ some
+terms.
+
+Just like other inputs, [the `<button>` tag can take both `name` and `value`
+attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#attr-name).
+
+```html
+<form action="/terms" method="post">
+  <p>Something about the terms ...</p>
+  <div>
+    <label for="name">Email: </label>
+    <input type="email" name="email" id="email" required>
+  </div>
+  <div>
+    <button type="submit" name="commit" value="accept">Accept</button>
+    <button type="submit" name="commit" value="reject">Reject</button>
+  </div>
+</form>
+```
+
+In addition to the `email` attribute, when the user submits the form, it will
+include a `commit` attribute that has a value of either `'accept'` or
+`'reject'`.
+
+Naming it `commit` is [a convention I'm borrowing from Rails's form
+helpers](https://guides.rubyonrails.org/v5.0/form_helpers.html#a-generic-search-form).
+You can name it whatever makes sense to you.