I have a button that submits a form to a flask server and runs a JS function. When the button is pressed the JS function runs, then it is overridden by the flask render_template function. I need the form to be hidden after server-side processing is done and the analyse div to be unhidden.

HTML:

JS button function:

// Function hides the form and unhides the 'analyse' div
// Another function reverses hide() function
function hide() {
    var index = document.getElementById('index');
    var analyse = document.getElementById('analyse');
    index.classList.add('hidden');
    analyse.classList.remove('hidden');
}

Server-side Python:

@app.route('/', methods=['GET','POST'])
def index():
    return render_template('index.html')

@app.route('/analyse', methods=['GET','POST'])
def analyse():
    # Validation and functions, etc.
    return render_template('index.html')

The JS should hide the form, but the Python makes it re-appear and hides the analyse div again (this is what I mean by "override").