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

Writing files

There are several modes in opening a file, and so far, we have only used the read(r) mode. To open a file for writing, we can use the following syntax:

var ins = fs.open(filePath, 'w');

This will create a new stream object that we can use to write new content to. For example, in our script we have a configuration that is in JSON object format. Let us assume that the configuration object can be changed during runtime and we need that state to be saved back to configuration. Let's say we need to save some new values to our configuration file.

var config = {
  debug: true,
  home: '/home/phantomjs',
  username: 'tarab'
};
var out = fs.open(filePath, 'w');
// File opened for writing
out.write(JSON.stringify(config, null, 4));
out.close();

phantom.exit(0);

After opening the file for writing, we use the write function and pass the string value of the JSON object to be written to the file. With this simple function call we have written a...