Casper-nodejs NPM

casper-nodejs

Control CasperJS from your nodejs application.

Objective

Allow you to write powerful scraping scripts in nodeJs, by using CasperJS from nodeJs.

Requirements

PhantomJS
CasperJs
NodeJS

How to Use

Installation

Install the dependencies:

sudo npm install -g phantomjs casperjs
npm install

Usage

Create a nodejs script.

var casper_nodejs = require('../../index.js');

var url = "http://google.com";
// load the page refered with 'url' with casper
var casper = casper_nodejs.create(url, {});

// once the page is loaded, execute that in our current nodejs context
casper.then(function executed_in_this_context() {
  console.log("page loaded");
});

// then, execute that in casperjs, and the second callback in the current nodejs context
casper.then(function executed_in_casperjs_context() {
  return 42;
}, function executed_in_this_context(ret) {
  console.log("it works: " + ret);
  
  // casper.exit() can be placed here too, instead of in the bottom :)
  // casper.exit();
});

// exit casper after executing the 2 previous 'then'
casper.exit();

How it works

casper.create() spawns a child (casper-child), which:

listens on port 8085, waiting for POST requests
keep the casperjs context open (by doing casper.waitFor() in loop)
creates a lock file once the server is listening ( /tmp/casper-nodejs-XXXXX)

In the nodejs context:

All the casper.then() and casper.exit() calls are added in an array.
The call to casper.run() tells to the library that now it can send the POST requests to the child
If the lock file hasn't been created, casper.run() call setTimeout in order to verify in an async way, until the file is created.