Make a client POST request to Flask render_template endpoint
For anyone who has such a use case too, ensure that you use a method post like below (put it inside the index.html in this case):
<script> $(document).ready(function() { $("#clickMe").on('click', function() { console.log('clicked, making a request') post('/', {'key-1': 'val-1'}); }) }) function post(path, params, method='post') { const form = document.createElement('form'); form.method = method; form.action = path; for (const key in params) { if (params.hasOwnProperty(key)) { const hiddenField = document.createElement('input'); hiddenField.type = 'hidden'; hiddenField.name = key; hiddenField.value = params[key]; form.appendChild(hiddenField); } } document.body.appendChild(form); form.submit(); } </script>This creates a hidden form on the web page and then submits the form, from then onwards, flask processes everything properly.