July 2017
Intermediate to advanced
398 pages
11h 54m
Chinese
Content preview from Python数据处理
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236
｜
第
11
章
由于网站正在运行
jQuery
，直接在控制台标签第一行中输入下面的代码
：
$('div.content-block');
敲击回车键，控制台会响应那个元素。点击控制台中的响应，你会看到子元素，以及该元
素的子元素。可以同一些基本的
jQuery
（例如，
$(elem)；
）一起使用
CSS
选择器，来选择
其他页面上的元素。使用
$
和括号会告诉
jQuery
我们正在寻找一个与括号中的字符串传递
的选择器相匹配的元素。
你能使用控制台来选择
ID
为
weAreFairphone
的
div
吗？你是否只能选择页面上的锚标记
（
a
）？在控制台中尝试一下。命令行和
jQuery
提供了一个简单的方式来使用
CSS
选择器
或标签名称同页面上实际的元素交互，并从这些元素中拉取内容。但是这与
Python
有什么
关系呢？
因为
jQuery
改变了人们对
CSS
选择器用处的看法，
Python
抓取库现在使用这些选择器来
遍历和寻找网页中的元素。就像你可以在浏览器控制台中使用简单的
jQuery
选择器，你也
可以在
Python
抓取器代码中使用它。如果想学习更多的
jQuery
知识，建议你访问
jQuery
学习中心
（
https://learn.jquery.com/
），或在
Codecademy
（
http://www.codecademy.com/en/
tracks/jquery
）或
Code School
（
https://www.codeschool.com/courses/try-jquery
）上学习课程。
如果碰到一个没有使用
jQuery ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.