Class: Ask::WebFetch::Backends::AttachedBrowser::Page

Inherits:
Object
  • Object
show all
Defined in:
lib/ask/web_fetch/backends/attached_browser.rb

Overview

One tab in the attached browser, closed with #close. Speaks just enough CDP for the Browser backend: navigate, read title/URL/HTML, and report the main-document HTTP status.

Defined Under Namespace

Classes: Network

Instance Method Summary collapse

Constructor Details

#initialize(client, timeout:, restore_focus_to: nil) ⇒ Page

Returns a new instance of Page.



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 50

def initialize(client, timeout:, restore_focus_to: nil)
  @client = client
  @timeout = timeout
  @restore_focus_to = restore_focus_to
  @target_id = @client.command('Target.createTarget', url: 'about:blank')['targetId']
  @session = @client.session(
    @client.command('Target.attachToTarget', targetId: @target_id, flatten: true)['sessionId']
  )
  # Subscribed BEFORE any navigation so the idle wait sees the
  # page's real load traffic (lazy SPAs render in waves).
  @network = Network.new(self)
end

Instance Method Details

#body ⇒ Object 



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 84

def body
  evaluate('document.documentElement.outerHTML') || ''
end

#close ⇒ Object 



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 95

def close
  @client.command('Target.closeTarget', targetId: @target_id)
rescue Ferrum::Error
  nil
ensure
  # The attached dev Chrome window steals focus when a tab is
  # created; give it back once the tab is gone — but only to an
  # app that ISN'T Chrome, so a fetch while the user is already
  # looking at Chrome doesn't ping-pong.
  FocusRestorer.restore_frontmost(@restore_focus_to)
end

#evaluate(expression) ⇒ Object 



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 107

def evaluate(expression)
  response = @session.command('Runtime.evaluate', expression: expression, returnByValue: true)
  # Ferrum's command() unwraps CDP's outer "result", leaving
  # { "result" => RemoteObject, "exceptionDetails" => ... }.
  response.dig('result', 'value')
end

#go_to(url) ⇒ Object

Navigates and does not return until the document has actually loaded — Page.navigate only starts the navigation, and reading the page before it commits yields an empty document (the very failure mode this class exists to avoid).



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 67

def go_to(url)
  result = @session.command('Page.navigate', url: url)
  error = result['errorText']
  if error && error != 'net::ERR_ABORTED'
    raise Ferrum::StatusError, "Request to #{url} failed (#{error})"
  end

  wait_for_load
end

#network ⇒ Object

Minimal network facade for the Browser backend: status from the Navigation Timing API, idle from CDP Network events (subscribed in the constructor, before navigation).



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 91

def network
  @network
end

#title ⇒ Object 



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 76

def title
  evaluate('document.title')
end

#url ⇒ Object 



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# File 'lib/ask/web_fetch/backends/attached_browser.rb', line 80

def url
  evaluate('location.href')
end