How to render a partial from javascript

I have a select that gets populated depending on the selection in a different select To do this, I did what is recommended in Railscast #88 on 'Dynamic Select Menus'.

But now I need to render a partial, passing in the value selected in each of those selects. I can't figure out how to simply trigger 开发者_Go百科a method call from the :onchange event in the select, so I'm thinking I need to call render :partial from within the javascript handler that detects the selects change event. But I can't figure out how. I tried the following in the javascript method (in the .js.erb file) but it doesn't work as hoped:

function staffSelected() {
    $('date_area').show();
    <% render :partial => "calendar" -%>
}

Anyone have a good solution?

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I think this is what you are looking for. I am rendering the partial within a DIV with "colors" ID, the partial is rendered only if the selected radio button's value is red:

<script language="javascript" type="text/javascript">
jQuery(function($){
  $('#radio-buttons input[type=radio]').click(function() {
    if ($(this).attr("value") === "red") {
      $("#colors").html('#{escape_javascript(render :partial => "colors")}');
    }
  });
});
</script>

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You can't render a partial inside of JavaScript to detect change events. Ruby is server side, and JavaScript is client side. By the time your JavaScript runs, your Ruby has already been parsed into regular ol' HTML.

Your best bet is to do the following:

Use an AJAX control (there are Prototype/scriptaculous ones) to hit your server in the onchange event. Your server can send back RJS to update the other dropdowns, or it can return back standard JSON and you can populate the other dropdowns manually in the onSuccess method of the AJAX call.