Book Image

Getting Started with PhantomJS

By : Aries beltran
Book Image

Getting Started with PhantomJS

By: Aries beltran

Overview of this book

PhantomJS is a headless WebKit browser with JavaScript API that allows you to create new ways to automate web testing. PhantomJS is currently being used by a large number of users to help them integrate headless web testing into their development processes. It also gives you developers a new framework to create web-based applications, from simple web manipulation to performance measurement and monitoring.A step step-by by-step guide that will help you develop new tools for solving web and testing problems in an effective and quick way. The book will teach you how to use and maximize PhantomJS to develop new tools for web scrapping, web performance measurement and monitoring, and headless web testing. This book will help you understand PhantomJS’ scripting API capabilities and strengths.This book starts by looking at PhantomJS’ JavaScript API, features, and basic execution of scripts. Throughout the book, you will learn details to help you write scripts to manipulate web documents and fully create a web scrapping tool.Through its practical approach, this book strives to teach you by example, where each chapter focuses on the common and practical usage of PhantomJS, and how to extract meaningful information from the web and other services.By the end of the book, you will have acquired the skills to enable you to use PhantomJS for web testing, as well as learning the basics of Jasmine, and how it can be used with PhantomJS.
Table of Contents (13 chapters)
12
Index

Screenshot dimensions

PhantomJS renders the entire page depending on the size of the page or how it was supposed to be rendered in a browser. Different sites render differently. For example, if we capture a Wikipedia page in a normal browser, it will render something similar to the following screenshot:

Screenshot dimensions

The browser loads everything, but we can only see the viewable area in the browser, and we must scroll down to see everything else. In PhantomJS, it renders everything in one image. If we use our script and capture the screenshot of the preceding URL, it will give us an image with a dimension size of 777 pixels wide and 71,366 pixels long.

Having these gigantic images may cause some problems for viewing. PhantomJS allows setting the dimension size of what we have to capture. We can use the clipRect property of the WebPage object.

Screenshot dimensions

Let us say we want to limit the size of the rectangle to 800 pixels in width and 800pixels in height. We also need to define the coordinate the clipping will start...