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Javascript

Overview

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

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.

How does it work?

All the pagy*_js helpers render their component on the client side. The helper methods serve just a minimal HTML tag that contains a data-pagy attribute. A small javascript file (that you must include in your assets) will take care to convert the data embedded in the data-pagy attribute and make it work in the browser.

You can pick and configure a Javascript File depending on the environment of your app.

Notice The javascript file is required only for the pagy*_js helpers. Just using 'data-remote="true"' without any pagy*_js helper works without any javascript file.

Faster performance with the oj gem

Although it’s not a requirement, you should consider adding 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.)

CAVEATS

Overriding

Any *_js helper is composed by a HTML part and some javascript code that work in sync. Overriding is likely going to break in the future as soon as the relation between the helper and the functions will change in a next release (e.g. arguments, naming, etc.), so overriding is not recommended.

HTML fallback

Notice that if the client browser doesn’t support Javascript or if it is disabled, certain helpers will serve nothing useful for the user. If your app does not require Javascript support and you still want to use javascript helpers, then you should consider implementing your own HTML fallback. For example:

<noscript><%== pagy_nav(@pagy) %></noscript>

Javascript Navs

The following pagy*_nav_js helpers:

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

Installation instructions

  1. Load the Javascript assets.
  2. Add the relevant extra
  3. Use JS helper in a View

See extras for general usage info.

1. Load / Initialise Pagy Javascript

The strategy might vary, depending on what you’re using: sprockets / or bundlers like (webpack-esbuild-rollup etc) / importmaps / propshaft etc - see Javascript Readme Instructions for installation and initialization details.

2. Add the relevant extra

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'

This will make available, the below helpers:

3. Use the JS helper in a View

Use one of 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 multiple 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, or even pass it to the pagy*_nav_js helper as an optional keyword argument.

For example:

# globally
Pagy::DEFAULT[: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 )
or pass it to the helper
<%== pagy_nav_js(@pagy, steps: {...}) %>

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:

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

pagy*_nav_js(pagy, …)

The method accepts also a few optional keyword arguments:

CAVEATS: the pagy_bootstrap_nav_js and pagy_semantic_nav_js assign a class attribute to their links, so do not add another class attribute with the :link_extra. That would be illegal HTML and ignored by most browsers.

pagy*_combo_nav_js(pagy, …)

The method accepts also a couple of optional keyword arguments:

CAVEATS: the pagy_semantic_combo_nav_js assigns a class attribute to its links, so do not add another class attribute with the :link_extra. That would be illegal HTML and ignored by most browsers.

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 an AJAX-rendered pagy_bootstrap_nav_js:

In 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

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

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

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

<%== pagy_bootstrap_nav_js(@pagy) %>

In 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.