在rails中，我正在发送一个var以查看，但是在js文件中为nil

Question

I'm sending a var in rails to use it in the view, I have a js file name charts.js.erb that is called and I need to use the var in that js file but is nil

in my controller a have the method

  def index
    @asd = 'hellow'
  end

in my view i can do

.div= @asd

but in my javascript file

alert('<%= @asd %>');

@asd var is nil, i've tested using other ruby code an works, but the vars doesn't work

Answer 1

That's not how ERB works with JavaScript. The JS files are generated before runtime, so they do not have access to dynamic server values like that.

The pattern that I usually follow is to place the server-generated value somewhere in the DOM for the JS to pick up.

<div id="asd" data-asd="<%= @asd %>">

Then if you're using jQuery, for example:

var asd = $('#asd').data('asd');