Gaining access to the rails variables inside js file

[ytbryan]

Hi folks,

does anyone know how do I access the rails variables via erb inside a .js file. I am not looking for an alternate solution like using the gon rubygem.

From #1256, I know I can access the ActionController' helpers using:

<% helper = ActionController::Base.helpers %>
<% helpers.asset_pack_path('rails.png') %>

How do I print the rails variable (@something) of my index action of Actioncontroller, inside the js.erb?

For instance,

#inside PagesController.rb
def index
@something = "something" 
end

//packs/something.js.erb
console.log("<%= @something %>")

What am I missing here? Appreciate any pointers. Thank you!

[haffla]

In a standard (non-Webpacker) .js or .js.erb file you cannot access controller instance variables either as far as I know.

If you cannot use gon, I guess you have to do it manually and set the variables in the view and access them then in your Javascript.

[ytbryan]

Yup, I am not looking at non-webpacker setup but mainly looking at app/javascript/packs/*js.erb

I was hoping that Rails' ujs has something available for direct usage.

[gauravtiwari]

Not sure if that's easily doable unless you extend the ActionController::Base.helpers with your own set of helpers, which is a bit repetitive and probably not intuitive if you want to share instance variables - https://github.com/rails/webpacker/blob/master/lib/webpacker/railtie.rb#L64.

Is it not possible to use data-attrs i.e. declaring data-attrs in the view and reading it back in JS?

<div data-attrs="{something: "foo"}" id="foo">
</div>

const foo = JSON.parse(document.getElementById('foo').dataset.attrs);
foo.something

[sharang-d]

@ytbryan Did that work for you? Can we close this?

[anon987654321]

If I may ask, what's really the point of Erb in JS if we can't access Rails variables?