啥是pjax?

pjax = pushState + ajax

=======================

pjax是一個jQuery插件，它使用ajax和pushState經過真正的永久連接，頁面標題和後退按鈕提供快速瀏覽體驗。

pjax的工做方式是經過ajax從服務器獲取HTML，而後用加載的HTML替換頁面上容器元素的內容。而後，它使用pushState更新瀏覽器中的當前URL。因爲如下兩個緣由，這致使頁面導航更快：

• 沒有頁面資源（JS，CSS）被從新執行或從新應用；
• 若是將服務器配置爲使用pjax，則它只能渲染部分頁面內容，所以避免了可能昂貴的完整佈局渲染。

該項目的狀態

此時，jquery-pjax基本上再也不須要維護。它可能會繼續收到重要的錯誤修復，可是_其功能集被凍結_，不太可能得到新功能或加強功能。

安裝

pjax取決於jQuery 1.8或更高版本。

$ npm install jquery-pjax

standalone script

Download and include jquery.pjax.js in your web page:

curl -LO https://raw.github.com/defunkt/jquery-pjax/master/jquery.pjax.js

Usage

$.fn.pjax

The simplest and most common use of pjax looks like this:

$(document).pjax('a', '#pjax-container')

This will enable pjax on all links on the page and designate the container as #pjax-container.

If you are migrating an existing site, you probably don't want to enable pjax
everywhere just yet. Instead of using a global selector like a, try annotating
pjaxable links with data-pjax, then use 'a[data-pjax]' as your selector. Or,
try this selector that matches any <a data-pjax href=> links inside a `<div
data-pjax>` container:

$(document).pjax('[data-pjax] a, a[data-pjax]', '#pjax-container')

Server-side configuration

Ideally, your server should detect pjax requests by looking at the special
X-PJAX HTTP header, and render only the HTML meant to replace the contents of
the container element (#pjax-container in our example) without the rest of
the page layout. Here is an example of how this might be done in Ruby on Rails:

def index
  if request.headers['X-PJAX']
    render :layout => false
  end
end

If you'd like a more automatic solution than pjax for Rails check out [Turbolinks][].

Check if there is a pjax plugin for your favorite server framework.

Also check out RailsCasts #294: Playing with PJAX.

Arguments

The synopsis for the $.fn.pjax function is:

$(document).pjax(selector, [container], options)

1. selector is a string to be used for click event delegation.
2. container is a string selector that uniquely identifies the pjax container.
3. options is an object with keys described below.

pjax options

key	default	description
timeout	650	ajax timeout in milliseconds after which a full refresh is forced
push	true	use [pushState][] to add a browser history entry upon navigation
replace	false	replace URL without adding browser history entry
maxCacheLength	20	maximum cache size for previous container contents
version		a string or function returning the current pjax version
scrollTo	0	vertical position to scroll to after navigation. To avoid changing scroll position, pass false.
type	"GET"	see [$.ajax][]
dataType	"html"	see [$.ajax][]
container		CSS selector for the element where content should be replaced
url	link.href	a string or function that returns the URL for the ajax request
target	link	eventually the relatedTarget value for pjax events
fragment		CSS selector for the fragment to extract from ajax response

You can change the defaults globally by writing to the $.pjax.defaults object:

$.pjax.defaults.timeout = 1200

$.pjax.click

This is a lower level function used by $.fn.pjax itself. It allows you to get a little more control over the pjax event handling.

This example uses the current click context to set an ancestor element as the container:

if ($.support.pjax) {
  $(document).on('click', 'a[data-pjax]', function(event) {
    var container = $(this).closest('[data-pjax-container]')
    var containerSelector = '#' + container.id
    $.pjax.click(event, {container: containerSelector})
  })
}

NOTE Use the explicit $.support.pjax guard. We aren't using $.fn.pjax so we should avoid binding this event handler unless the browser is actually going to use pjax.

$.pjax.submit

Submits a form via pjax.

$(document).on('submit', 'form[data-pjax]', function(event) {
  $.pjax.submit(event, '#pjax-container')
})

$.pjax.reload

Initiates a request for the current URL to the server using pjax mechanism and replaces the container with the response. Does not add a browser history entry.

$.pjax.reload('#pjax-container', options)

$.pjax

Manual pjax invocation. Used mainly when you want to start a pjax request in a handler that didn't originate from a click. If you can get access to a click event, consider $.pjax.click(event) instead.

function applyFilters() {
  var url = urlForFilters()
  $.pjax({url: url, container: '#pjax-container'})
}

Events

All pjax events except pjax:click & pjax:clicked are fired from the pjax
container element.

event	cancel	arguments	notes
event lifecycle upon following a pjaxed link
pjax:click	✔︎	options	fires from a link that got activated; cancel to prevent pjax
pjax:beforeSend	✔︎	xhr, options	can set XHR headers
pjax:start		xhr, options
pjax:send		xhr, options
pjax:clicked		options	fires after pjax has started from a link that got clicked
pjax:beforeReplace		contents, options	before replacing HTML with content loaded from the server
pjax:success		data, status, xhr, options	after replacing HTML content loaded from the server
pjax:timeout	✔︎	xhr, options	fires after options.timeout; will hard refresh unless canceled
pjax:error	✔︎	xhr, textStatus, error, options	on ajax error; will hard refresh unless canceled
pjax:complete		xhr, textStatus, options	always fires after ajax, regardless of result
pjax:end		xhr, options
event lifecycle on browser Back/Forward navigation
pjax:popstate			event direction property: "back"/"forward"
pjax:start		null, options	before replacing content
pjax:beforeReplace		contents, options	right before replacing HTML with content from cache
pjax:end		null, options	after replacing content

pjax:send & pjax:complete are a good pair of events to use if you are implementing a
loading indicator. They'll only be triggered if an actual XHR request is made,
not if the content is loaded from cache:

$(document).on('pjax:send', function() {
  $('#loading').show()
})
$(document).on('pjax:complete', function() {
  $('#loading').hide()
})

An example of canceling a pjax:timeout event would be to disable the fallback
timeout behavior if a spinner is being shown:

$(document).on('pjax:timeout', function(event) {
  // Prevent default timeout redirection behavior
  event.preventDefault()
})

Advanced configuration

Reinitializing plugins/widget on new page content

The whole point of pjax is that it fetches and inserts new content without
refreshing the page. However, other jQuery plugins or libraries that are set to
react on page loaded event (such as DOMContentLoaded) will not pick up on
these changes. Therefore, it's usually a good idea to configure these plugins to
reinitialize in the scope of the updated page content. This can be done like so:

$(document).on('ready pjax:end', function(event) {
  $(event.target).initializeMyPlugin()
})

This will make $.fn.initializeMyPlugin() be called at the document level on
normal page load, and on the container level after any pjax navigation (either
after clicking on a link or going Back in the browser).

Response types that force a reload

By default, pjax will force a full reload of the page if it receives one of the
following responses from the server:

• Page content that includes <html> when fragment selector wasn't explicitly
  configured. Pjax presumes that the server's response hasn't been properly
  configured for pjax. If fragment pjax option is given, pjax will extract the
  content based on that selector.
• Page content that is blank. Pjax assumes that the server is unable to deliver
  proper pjax contents.
• HTTP response code that is 4xx or 5xx, indicating some server error.

Affecting the browser URL

If the server needs to affect the URL which will appear in the browser URL after
pjax navigation (like HTTP redirects work for normal requests), it can set the
X-PJAX-URL header:

def index
  request.headers['X-PJAX-URL'] = "http://example.com/hello"
end

Layout Reloading

Layouts can be forced to do a hard reload when assets or html changes.

First set the initial layout version in your header with a custom meta tag.

<meta http-equiv="x-pjax-version" content="v123">

Then from the server side, set the X-PJAX-Version header to the same.

if request.headers['X-PJAX']
  response.headers['X-PJAX-Version'] = "v123"
end

Deploying a deploy, bumping the version constant to force clients to do a full reload the next request getting the new layout and assets.