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Javascript

Javascript

Overview

A few helpers use javascript, and they are clearly recognizable by the js suffix:

  • pagy*_nav_js
  • pagy*_combo_nav_js
  • pagy_items_selector_js

If you use any of them you should follow this documentation, if not, consider that Javascript is not used anywhere else, so you can skip this.

Usage

Load the pagy.js file, and run Pagy.init() on window-load and eventually on AJAX-load.

CAVEATS

  • If you override any *_js helper, ensure to override/enforce the relative javascript function, even with a simple copy and paste. If the relation between the helper and the function changes in a next release (e.g. arguments, naming, etc.), your app will still work with your own overriding even without the need to update it.
  • See also Preventing crawlers to follow look-alike links

Add the oj gem

Although it's not a requirement, if you are on ruby 2.0+ (not jruby), and if you use any *_nav_js helper, you should add the gem 'oj' to your Gemfile. When available, Pagy will automatically use it to boost the performance. (Notice: It does nothing for normal, non-js helpers.)

In rails apps

With the asset pipeline

If your app uses the sprocket asset-pipeline, add the assets-path in the pagy.rb initializer:

Rails.application.config.assets.paths << Pagy.root.join('javascripts')

Add the pagy javascript to the application.js:

//= require pagy

Add an event listener for turbolinks:

window.addEventListener("turbolinks:load", Pagy.init);

or a generic one if your app doesn't use turbolinks:

window.addEventListener("load", Pagy.init);

With Webpacker

If your app uses Webpacker, ensure that the webpacker erb loader is installed:

bundle exec rails webpacker:install:erb

Then create a pagy.js.erb in order to render the content of pagy.js and add the event listener into it:

<%= Pagy.root.join('javascripts', 'pagy.js').read %>
window.addEventListener("load", Pagy.init)

and import it in app/javascript/application.js:

import '../src/javascripts/pagy.js.erb'

Notice:

  • You may want to use turbolinks:load if your app uses turbolinks despite webpacker
  • or you may want just export { Pagy } from the pagy.js.erb file and import and use it somewhere else.
  • You may want to expose the Pagy namespace, if you need it available elsewhere (e.g. in js.erb templates): 
    global.Pagy = Pagy

In non-rails apps

Ensure the pagy/extras/javascripts/pagy.js script gets served with the page.

Add an event listener like:

window.addEventListener('load', Pagy.init);

or execute the Pagy.init() using jQuery:

$( window ).load(function() {
  Pagy.init()
});

Javascript Navs

The following pagy*_nav_js helpers:

  • pagy_nav_js
  • pagy_bootstrap_nav_js
  • pagy_bulma_nav_js
  • pagy_foundation_nav_js
  • pagy_materialize_nav_js
  • pagy_semantic_nav_js

look like a normal pagy*_nav but have a few added features:

  1. Client-side rendering
  2. Optional responsiveness
  3. Better performance and resource usage (see Maximizing Performance)

Here is a screenshot (from the bootstrapextra) showing responsiveness at different widths:

bootstrap_nav_js

Synopsis

See extras for general usage info.

In the pagy.rb initializer, require the specific extra for the style you want to use:

# you only need one of the following extras
require 'pagy/extras/bootstrap'
require 'pagy/extras/bulma'
require 'pagy/extras/foundation'
require 'pagy/extras/materialize'
require 'pagy/extras/navs'
require 'pagy/extras/semantic'
require 'pagy/extras/uikit'

Use the pagy*_nav_js helpers in any view:

<%== pagy_nav_js(@pagy) %>
<%== pagy_bootstrap_nav_js(@pagy) %>
<%== pagy_bulma_nav_js(@pagy) %>
<%== pagy_foundation_nav_js(@pagy) %>
<%== pagy_materialize_nav_js(@pagy) %>
<%== pagy_semantic_nav_js(@pagy) %>

Variables

Variable Description Default
:steps Hash variable to control multipe pagy :size at different widths false

:steps

The :steps is an optional non-core variable used by the pagy*_nav_js navs. If it's false, the pagy*_nav_js will behave exactly as a static pagy*_nav respecting the single :size variable, just faster and lighter. If it's defined as a hash, it allows you to control multiple pagy :size at different widths.

You can set the :steps as a hash where the keys are integers representing the widths in pixels and the values are the Pagy :size variables to be applied for that width.

As usual, depending on the scope of the customization, you can set the variables globally or for a single pagy instance.

For example:

# globally
Pagy::VARS[:steps] = { 0 => [2,3,3,2], 540 => [3,5,5,3], 720 => [5,7,7,5] }

# or for a single instance
pagy, records = pagy(collection, steps: { 0 => [2,3,3,2], 540 => [3,5,5,3], 720 => [5,7,7,5] } )

# or use the :size as any static pagy*_nav
pagy, records = pagy(collection, steps: false )

The above statement means that from 0 to 540 pixels width, Pagy will use the [2,3,3,2] size, from 540 to 720 it will use the [3,5,5,3] size and over 720 it will use the [5,7,7,5] size. (Read more about the :size variable in the How to control the page links section).

IMPORTANT: You can set any number of steps with any arbitrary width/size. The only requirement is that the :steps hash must contain always the 0 width or a Pagy::VariableError exception will be raised.

Setting the right sizes

Setting the widths and sizes can create a nice transition between widths or some apparently erratic behavior.

Here is what you should consider/ensure:

  1. The pagy size changes in discrete :steps, defined by the width/size pairs.

  2. The automatic transition from one size to another depends on the width available to the pagy nav. That width is the internal available width of its container (excluding eventual horizontal padding).

  3. You should ensure that - for each step - each pagy :size produces a nav that can be contained in its width.

  4. You should ensure that the minimum internal width for the container div be equal (or a bit bigger) to the smaller positive width. (540 pixels in our previous example).

  5. If the container width snaps to specific widths in discrete steps, you should sync the quantity and widths of the pagy :steps to the quantity and internal widths for each discrete step of the container.

Javascript Caveats

In case of a window resize, the pagy_*nav_js elements on the page are re-rendered (when the container width changes), however if the container width changes in any other way that does not involve a window resize, then you should re-render the pagy element explicitly. For example:

document.getElementById('my-pagy-nav-js').render();

Javascript Combo Navs

The following pagy*_combo_nav_js offer an alternative pagination UI that combines navigation and pagination info in a single compact element:

  • pagy_combo_nav_js
  • pagy_bootstrap_combo_nav_js
  • pagy_bulma_combo_nav_js
  • pagy_foundation_combo_nav_js
  • pagy_materialize_combo_nav_js
  • pagy_semantic_combo_nav_js

They are the fastest and lightest nav on modern environments, recommended when you care about efficiency and server load (see Maximizing Performance).

Here is a screenshot (from the bootstrap extra):

bootstrap_combo_nav_js

Synopsis

See extras for general usage info.

In the pagy.rb initializer, require the specific extra for the style you want to use:

# you only need one of the following extras
require 'pagy/extras/bootstrap'
require 'pagy/extras/bulma'
require 'pagy/extras/foundation'
require 'pagy/extras/materialize'
require 'pagy/extras/navs'
require 'pagy/extras/semantic'
require 'pagy/extras/uikit'

Use the pagy*_combo_nav_js helpers in any view:

<%== pagy_combo_nav_js(@pagy) %>
<%== pagy_bootstrap_combo_nav_js(@pagy) %>
<%== pagy_bulma_combo_nav_js(@pagy) %>
<%== pagy_foundation_combo_nav_js(@pagy) %>
<%== pagy_materialize_combo_nav_js(@pagy) %>
<%== pagy_semantic_combo_nav_js(@pagy) %>

Methods

*_nav_js(pagy, ...)

All *_nav_js methods can take an extra id argument, which is used to build the id attribute of the nav tag. Since the internal automatic id generation is based on the code line where you use the helper, you must pass an explicit id if you are going to use more than one *_js call in the same line for the same file.

Notice: passing an explicit id is also a bit faster than having pagy to generate one.

Using AJAX

If you AJAX-render any of the javascript helpers mentioned above, you should also execute Pagy.init(container_element); in the javascript template. Here is an example for a pagy_bootstrap_nav_js AJAX-render:

pagy_remote_nav_js controller action (notice the link_extra to enable AJAX):

def pagy_remote_nav_js
  @pagy, @records = pagy(Product.all, link_extra: 'data-remote="true"')
end

pagy_remote_nav_js.html.erb template for non-AJAX render (first page-load):

<div id="container">
  <%= render partial: 'nav_js' %>
</div>

_nav_js.html.erb partial shared for AJAX and non-AJAX rendering:

<%== pagy_bootstrap_nav_js(@pagy) %>

pagy_remote_nav_js.js.erb javascript template used for AJAX:

$('#container').html("<%= j(render 'nav_js')%>");
Pagy.init(document.getElementById('container'));

IMPORTANT: The document.getElementById('container') argument will re-init the pagy elements just AJAX-rendered in the container div. If you miss it it will not work with AJAX.