Question

A Rails layout

<%= image_tag("logo.png", :alt => "Sample App", :class => "round") %>

will render as the HTML

<img alt="Sample App" class="round" src="/images/logo.png" />

Will web pages load noticeably slower if they have to render a page versus getting the HTML directly? I’m trying to figure out the advantage of writing HTML in Ruby, except perhaps for convenience?

Answer 1

Advantage of dynamically generated HTML

In your simple example, it’s actually not important which one of your two options you use. Having a templating system like ERB is however necessary if as you want to create dynamic content, like in this example:

<%= image_tag(@user.logged_in? ? "logged_in.png" : "not_logged_in.png", :class => "login_status") %>

You cannot do this with static HTML.

Performance

Dynamically generating the HTML like this before serving it will obviously take a bit longer than serving static HTML. Rails has caching built in, however, so you can easily control the impact of this.