CasperJS是一个开源的导航脚本处理和测试工具，基于PhantomJS（前端自动化测试工具）编写。CasperJS简化了完整的导航场景的过程定义，提供了用于完成常见任务的实用的高级函数、方法和语法。
CasperJS 的官方文档地址：http://casperjs.readthedocs.io/en/latest/#casperjs-documentation
本文大部分为翻译官方的文档

安装

需要先安装PhantomJS 19.1或者更新的版本 installation instructions for PhantomJS
需要Python 2.6 或者更新的版本
windows下载文件为 https://github.com/casperjs/casperjs/zipball/master
其他OS的安装请参考官方文档： http://casperjs.readthedocs.io/en/latest/installation.html

快速开始

一个简单的例子

var casper = require('casper').create();

casper.start('http://casperjs.org/', function() {
    this.echo(this.getTitle());
});

casper.thenOpen('http://phantomjs.org', function() {
    this.echo(this.getTitle());
});

casper.run();

Run it (with python):

$ casperjs sample.js

Run it (with node):

$ node casperjs.js sample.js

Run it (with PhantomJS):

$ phantomjs casperjs.js sample.js

Run it (on windows):

C:\casperjs\bin> casperjs.exe sample.js

You should get something like this:

$ casperjs sample.js
CasperJS, a navigation scripting and testing utility for PhantomJS
PhantomJS: Headless WebKit with JavaScript API

一个复杂的例子

var links = [];
var casper = require('casper').create();

function getLinks() {
    var links = document.querySelectorAll('h3.r a');
    return Array.prototype.map.call(links, function(e) {
        return e.getAttribute('href');
    });
}

casper.start('http://google.fr/', function() {
   // Wait for the page to be loaded
   this.waitForSelector('form[action="/search"]');
});

casper.then(function() {
   // search for 'casperjs' from google form
   this.fill('form[action="/search"]', { q: 'casperjs' }, true);
});

casper.then(function() {
    // aggregate results for the 'casperjs' search
    links = this.evaluate(getLinks);
    // now search for 'phantomjs' by filling the form again
    this.fill('form[action="/search"]', { q: 'phantomjs' }, true);
});

casper.then(function() {
    // aggregate results for the 'phantomjs' search
    links = links.concat(this.evaluate(getLinks));
});

casper.run(function() {
    // echo results in some pretty fashion
    this.echo(links.length + ' links found:');
    this.echo(' - ' + links.join('\n - ')).exit();
});

Run it:

$ casperjs googlelinks.js
20 links found:
 - https://github.com/casperjs/casperjs
 - https://github.com/casperjs/casperjs/issues/2
 - https://github.com/casperjs/casperjs/tree/master/samples
 - https://github.com/casperjs/casperjs/commits/master/
 - http://www.facebook.com/people/Casper-Js/100000337260665
 - http://www.facebook.com/public/Casper-Js
 - http://hashtags.org/tag/CasperJS/
 - http://www.zerotohundred.com/newforums/members/casper-js.html
 - http://www.yellowpages.com/casper-wy/j-s-enterprises
 - http://local.trib.com/casper+wy/j+s+chinese+restaurant.zq.html
 - http://www.phantomjs.org/
 - http://code.google.com/p/phantomjs/
 - http://code.google.com/p/phantomjs/wiki/QuickStart
 - http://svay.com/blog/index/post/2011/08/31/Paris-JS-10-%3A-Introduction-%C3%A0-PhantomJS
 - https://github.com/ariya/phantomjs
 - http://dailyjs.com/2011/01/28/phantoms/
 - http://css.dzone.com/articles/phantom-js-alternative
 - http://pilvee.com/blog/tag/phantom-js/
 - http://ariya.blogspot.com/2011/01/phantomjs-minimalistic-headless-webkit.html
 - http://www.readwriteweb.com/hack/2011/03/phantomjs-the-power-of-webkit.php

一个简单的测试例子

// hello-test.js
casper.test.begin("Hello, Test!", 1, function(test) {
  test.assert(true);
  test.done();
});

结果

$ casperjs test hello-test.js
Test file: hello-test.js
# Hello, Test!
PASS Subject is strictly true
PASS 1 test executed in 0.023s, 1 passed, 0 failed, 0 dubious, 0 skipped.

Logging

CasperJS 使用 casper.log() 函数用来log，有下面四种log level。和python 中的logging 很类似

debug
info
warning
error

一个简单的例子：

var casper = require('casper').create();
casper.log('plop', 'debug');
casper.log('plip', 'warning');

默认情况下这些log 是不会打印出来的，如果需要，你必须打开verbose 这个选项, 而且默认情况下loglevel 是error, 你可以通过logLevel来进行更改，如下：

var casper = require('casper').create({
    verbose: true
    logLevel: 'debug'
});

选择器

CasperJS支持两种操作DOM的选择器：

CSS3
XPath
下面的例子都是基于这个HTML页面

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>My page</title>
</head>
<body>
    <h1 class="page-title">Hello</h1>
    <ul>
        <li>one</li>
        <li>two</li>
        <li>three</li>
    </ul>
    <footer><p>©2012 myself</p></footer>
</body>
</html>

CSS3

下面这个例子是用来检查<h1 class="page-title">的元素是否存在

var casper = require('casper').create();
casper.start('http://domain.tld/page.html', function() {
    if (this.exists('h1.page-title')) {
        this.echo('the heading exists');
    }
});

casper.run();

CSS3 选择器的文章： http://www.w3school.com.cn/cssref/css_selectors.asp

Xpath

上面的例子一样可以用XPath来实现

casper.start('http://domain.tld/page.html', function() {
    this.test.assertExists({
        type: 'xpath',
        path: '//*[@class="plop"]'
    }, 'the element exists');
});

为了更方便的使用XPath，你可以使用selectXPath帮助

var x = require('casper').selectXPath;

casper.start('http://domain.tld/page.html', function() {
    this.test.assertExists(x('//*[@id="plop"]'), 'the element exists');
});

Trip

判断页面是否正确返回或者渲染完毕，可以用wait函数

casper.thenOpen(url, function initialAppearance() {
  casper.waitForText('Text in deep part of page or modal');
});

有篇讲 CasperJS做UT的文章很好，要做UT的可以去看看：
http://www.oschina.net/translate/simpler-ui-testing-with-casperjs
API 文档速查，截屏，后退什么的都在这里 http://casperjs.readthedocs.io/en/latest/#casperjs-documentation

CasperJS 自动化web操作