How to get data from server from javascript?

Question

I have a bar graph in my web app (drawn using javascript). It can be wider than the screen, so there are arrows that move the graph along the x-axis on a click (again made using javascript).

I would like to redraw the graph when the user clicks an arrow. The data manipulation performed to generate the graph is too complex to do on the client side, and I don't want to send it all at once, as that would be a waste if the user never decides to scroll.

Instead, on a click I would like to send a request to the server for the new data needed to draw the next portion of the graph. How can this be done?

Note: I only want to request the data, not a new page. The server side is Ruby on Rails v. 3.0.4.

Shreyas · Accepted Answer · 2011-03-08 18:42:50Z

1

You need Ajax for this. You could use the built-in Prototype or any other Javascript library to accomplish this. So, giving you an example using jQuery you could add a click handler

$('#target').click(function() {
  // Use the $.ajax or equivalent function to send a request to a method in your controller
});

So in this example, in your controller you could either mention the dom manipulation code in the method like below:

def target_method
  # Process data 
  # dom manipulation code
  render :update do |page|
    #use a rails javascript helper like replace_html or the likes
  end 
end

Or go the Unobtrusive Javascript way and insert the DOM manipulation code inside a js.erb file.

Here are a few helpful links

answered Mar 8, 2011 at 18:42

Shreyas

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2 Comments

providence Over a year ago

Thanks for your help. I will go with jQuery as you recommended as I am already using it. Including prototype at this point will cause it to fight over the '$' symbol with jQuery.

Shreyas Over a year ago

If you need to use both libraries you could use jQuery's noconflict method. api.jquery.com/jQuery.noConflict

Will Ayd · Accepted Answer · 2011-03-08 18:39:31Z

1

you will need to look into AJAX http://edgeguides.rubyonrails.org/ajax_on_rails.html

answered Mar 8, 2011 at 18:39

Will Ayd

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