Question

Is there anything wrong with setting a Rails variable inside a javascript function? I haven’t been able to google a definete answer and just wanted to make sure there’s not a catch or flaw I’m unaware of. I’m actually confused as to how this works at all – if javascript is executed on the client side, I wouldn’t have assume Rails would respond to a variable change in the view after the view is rendered..?

(example) I have multiple functions calling the same form and I have a need to know which function called the forms to do specific tasks in the controller method (session in this case is a cookie, but I also tried a local Rails variable and it works as well).

<script type="text/javascript">

    $('.open_new_item_form' ).click(function(){
     alert('<%= session[:item_form_type]%>');
        <% session[:item_form_type] = "from_new_item_click" %>
     alert('<%= session[:item_form_type]%>');
        var url = $(this).attr("href");
        $.ajax({
etc...

The alerts seem to indicate it works well. It will alert with the current valute and then the new “from_new_item” value after the set.

Thanks – just making sure

Answer 1

Part of the rendering process for rails is to evaluate all the erb code within that view. Once the evaluation of the code is completed, rails will then render the file(whether it is javascript, html, etc).

So when you say that you were surprised to see that rails could respond to a variable change, it’s because the view wasn’t actually rendered at that point… it was in the process of rendering.