render-vendor ships with PhantomRenderer, a Renderer implementation that uses a long-lived, parallel renderer process to load, manage, and render Pages.

We recommend using a ChromeRenderer whenever possible, as it implements more modern web standards & APIs, and its architecture is less prone to memory leaks. However, some use cases may be better suited to Phantom’s environment. The PhantomRenderer can achieve similar rendering speeds as the ChromeRenderer, so using it should not significantly impact performance.

⚠ BE CAREFUL: the PhantomRenderer boots a parallel PhantomJS process. It is not bound to your REPL / application’s lifecycle. Make sure to destroy() any PhantomRenderers you create.

PhantomRenderers extend the base Renderer class to support the following options:

Renderer#load(id, options):

PhantomRenderers may load HTML documents, either from raw HTML data passed in the load request, or fetched from a provided URL.

Several additional options will affect the initial paint, so they must be provided at load time.

Key Type Default value Description  
url* String - URL to load in the PhantomJS page.  
html* String - 8180 HTML source to set on the PhantomJS page.
dpi Number - Configure rendered dpi, for non-px size values.  
zoomFactor Number - Scales images when not rendering PDFs.  
viewportSize { width, height } - Sets viewport size to the provided width + height values.  

*At least one of html or url is required. html will take priority over url.


At render time, PhantomRenderers accept two options, which are used to make any final adjustments to the presented document’s rendered output:

Key Type Default value Description
format String html Inherited from Page#render. When html, calls to render() will return the rendered HTML source; otherwise, the PhantomRenderer will try to render a file in the given format.
filename String /tmp/${randomString} Inherited from Page#render. When rendering an output file, setting filename will direct the rendered output to the specified path; else the file will be rendered to a randomly generated path in the /tmp directory.
quality Number 75 Quality with which to render output (for PNG + JPEG types).
paperSize Object - PhantomJS primitive to set values like margin, orientation, headers and footers on the page. For more, see the PhantomJS paperSize docs.

format may be any of the following values:

  • html;
  • pdf;
  • png;
  • jpeg;
  • bmp;
  • ppm; or
  • gif (depending on what build of Qt used, see PhantomJS docs for more details)


To assist with debugging, PhantomRenderers emit the following events:

Event signature Value type Description
message(message) String The spawned PhantomJS process has written data to stdout.
error(error) String The spawned PhantomJS process has written data to stderr.


PhantomRenderer instances’ boot method makes use of several options that may be provided as attributes to the constructor. All options have reasonable defaults.

Key Type Default value Description
host String PhantomRenderer.DEFAULT_HOSTlocalhost Host on which to bind the PhantomJS webserver.
port String PhantomRenderer.DEFAULT_PORT8180 Port on which to bind the PhantomJS webserver.
bin String require('phantomjs-prebuilt').path Path to the PhantomJS binary to run.
binArgs [String] [] Arguments to pass to the command line invocation that spawns the PhantomJS process.

Headers & Footers:

render-vendor uses similar header & footer handling to the popular html-pdf. You can set it via paperSize as described in the PhantomJS docs, or they can be read from the HTML source.

To override default headers or footers on a specific page, you must create elements in your HTML with ids conforming to the following syntax:

<div id="pageHeader">Default header</div>
<div id="pageHeader-first">Header on first page</div>
<div id="pageHeader-2">Header on second page</div>
<div id="pageHeader-3">Header on third page</div>
<div id="pageHeader-last">Header on last page</div>
<div id="pageFooter">Default footer</div>
<div id="pageFooter-first">Footer on first page</div>
<div id="pageFooter-2">Footer on second page</div>
<div id="pageFooter-last">Footer on last page</div>

PhantomRenderer instances will substitute $page & $numPages text in headers / footers with the corresponding value.