ruby-on-rails - rand has the same value when wrapped inside erb tag

Question

I have a new rails app, with a controller Page. The root path is set to 'page#index'.

The app/views/page/index.html has this code:

<h1>Page#index</h1>
<p>Find me in app/views/page/index.html.erb</p>

<script>
    setInterval(() => {
        console.log(<%= rand %>)
    }, 1000)
</script>

Which is truely a bad practice, but I am just curious to know why the console.log(<%= rand %>) line prints the same number every time?

标签： ruby-on-rails

Answer 1

The template is rendered once. If you look at the source of the page you will see one fixed number in the JS code. Reload the page and it is a different number.

If you want a different number every time the JS function is executed you need to do it in JS:

setInterval(() => {
  console.log(Math.random())
}, 1000)