CasperJS is an open source navigation scripting and testing utility written in JavaScript that eases the process of defining navigation scenarios and provides functions for common tasks like filling forms, clicking links, taking screenshots, and testing websites. It uses the PhantomJS or SlimerJS headless browsers under the hood. The Casper API provides methods like start(), then(), run(), and exit() to control navigation and run test suites, as well as utilities like fill(), click(), evaluate(), and waitForSelector() to interact with pages.

1. CasperJS
Howard 2013/12/22

2. CasperJS
CasperJS is an open source navigation scripting & testing
utility written in Javascript for the PhantomJS WebKit
headless browser and SlimerJS (Gecko).
It eases the process of defining a full navigation scenario
and provides useful high-level functions, methods &
syntactic sugar

3. Doing common tasks
 such as:
 defining & ordering browsing navigation steps
 filling & submitting forms
 clicking & following links
 capturing screenshots of a page (or part of it)
 testing remote DOM
 logging events
 downloading resources, including binary ones
 writing functional test suites, saving results as JUnit XML
 scraping Web contents

4. Installation
 Prerequisites
 PhantomJS
 PhantomJS is a headless WebKit scriptable with a JavaScript API.
 It has fast and native support for various web standards: DOM handling, CSS selector, JSON, Canvas, and
SVG.
 http://phantomjs.org/download.html
 CasperJS

5. 目標
 列舉出目前 IPTECH TW
的目前可檢索的站台

6. A minimal scraping script
 What did we just do?
 we created a new Casper instance
 we started it and opened http://casperjs.org/
 once the page has been loaded, we asked to print
the title of that webpage (the content of its <title>
tag)
 then we opened another url, http://phantomjs.org/
 once the new page has been loaded, we asked to
print its title too
 we executed the whole process

7. start(), then(), run(), exit()

start()
 Signature: start(String url [, Function then])
 Configures and starts Casper, then open the provided url and optionally adds the step provided by the then argument

then()
 Signature: then(Function then)

run()
 Signature: run(fn onComplete[, int time])
 Runs the whole suite of steps and optionally executes a callback when they’ve all been done. Obviously, calling this method is
mandatory in order to run the Casper navigation suite.

exit()
 Signature: exit([int status])
 Exits PhantomJS with an optional exit status code.

Note that the current Casper instance automatically binds the this keyword for you within step functions

8. start(), then(), run(), exit()

9. start(), then(), run(), exit()
?

10. casper module – fill
 Signature: fill(String selector, Object values[, Boolean submit])
 Fills the fields of a form with given values and optionally submits it.
 Fields are referenced by their name attribute.

11. click
 click(Number x, Number y)
 click(String selector)
 Performs a click on the first element found matching the provided selector expression or
at given coordinates if two numbers are passed
 selector expression
 CSS3 selector strings
 Xpath expressions

12. evaluate
 Signature: evaluate(Function fn[, arg1[, arg2[, …]]])
 Evaluates an expression in the current page DOM context

13. Understanding evaluate()
 Think of the evaluate() method as a gate between the CasperJS environment and the
one of the page you have opened;
 Every time you pass a closure to evaluate(), you’re entering the page and execute code
as if you were using the browser console.

14. waitForSelector
 Signature: waitForSelector(String selector[, Function then, Function onTimeout, Number
timeout])
 Waits until an element matching the provided selector expression exists in remote DOM to
process any next step

15. references
 http://docs.casperjs.org/en/latest/quickstart.html
 http://docs.casperjs.org/en/latest/modules/index.html
 http://docs.casperjs.org/en/latest/modules/casper.html#start
 http://docs.casperjs.org/en/latest/modules/casper.html#then
 http://docs.casperjs.org/en/latest/modules/casper.html#run
 http://docs.casperjs.org/en/latest/modules/casper.html#exit
 http://docs.casperjs.org/en/latest/modules/casper.html#fill
 http://docs.casperjs.org/en/latest/selectors.html
 http://docs.casperjs.org/en/latest/modules/mouse.html#click