XPath // * [@ href]不僅刮取鏈接

Question

我使用XPath //*[@href]從網頁上刮取鏈接。但是，我注意到，除了頁面上的實際鏈接Selenium也刮javascript:void(0)。

爲什麼會發生這種情況？

如果您在http://google.com上運行此測試，您會發現45個鏈接 - 其中3個並非實際鏈接，而是javascript：void（0）。

如何解決？

更新：上http://google.com預期輸出（寫這篇文章的時間）如下：

1 = https://www.google.com/images/branding/product/ico/googleg_lodp.ico 
2 = https://www.google.com/ 
3 = https://www.google.com/setprefs?suggon=2&prev=https://www.google.com/?gws_rd%3Dssl&sig=0_OQUUDCX_hZxBr1qNxxxxxxxxxxxEH_4%3D 
4 = https://mail.google.com/mail/?tab=wm 
5 = https://www.google.com/imghp?hl=en&tab=wi&ei=3NfSWL2xxxxxxxBg&ved=0EKouCBgoAQ 
6 = https://www.google.com/intl/en/options/ 
7 = https://myaccount.google.com/?utm_source=OGB 
8 = https://www.google.com/webhp?tab=ww&ei=3NfSWL2DKpxxxxxxxg&ved=0EKkuCAIoAQ 
9 = https://maps.google.com/maps?hl=en&tab=wl 
10 = https://www.youtube.com/ 
11 = https://play.google.com/?hl=en&tab=w8 
12 = https://news.google.com/nwshp?hl=en&tab=wn&ei=3NfSWL2xxxxxxxxxxxBg&ved=0EKkuCAYoBQ 
13 = https://mail.google.com/mail/?tab=wm 
14 = https://drive.google.com/?tab=wo 
15 = https://www.google.com/calendar?tab=wc 
16 = https://plus.google.com/?gpsrc=ogpy0&tab=wX 
17 = https://translate.google.com/?hl=en&tab=wT 
18 = https://photos.google.com/?tab=wq&pageId=none 
19 = https://www.google.com/intl/en/options/ 
20 = http://www.google.com/shopping?hl=en&tab=wf&ei=3NxxxxxxxxxTYBg&ved=0EKkuCA0oDA 
21 = https://wallet.google.com/?tab=wa 
22 = https://www.google.com/finance?tab=we 
23 = https://docs.google.com/document/?usp=docs_alc 
24 = https://books.google.com/bkshp?hl=en&tab=wp&ei=3NfSWL2xxxxxxxxxxxBg&ved=0EKkuCBEoEA 
25 = https://www.blogger.com/?tab=wj 
26 = https://www.google.com/contacts/?hl=en&tab=wC 
27 = https://hangouts.google.com/ 
28 = https://keep.google.com/ 
29 = https://www.google.com/intl/en/options/ 
30 = https://accounts.google.com/ServiceLogin?hl=en&passive=true&continue=https://www.google.com/%3Fgws_rd%3Dssl 
----------------------- (removed) 
32 = https://www.google.com/url?q=https://www.google.com/intl/en_us/homepage/search/sp-firefox.html%3Futm_source%3Dgoogle.com%26utm_medium%3Dpushdown%26utm_content%3Dswitch%26utm_campaign%3Dffdse&source=hpp&id=190xx319&ct=7&usg=AFxxxxxxxxbZR_QouKfSxxxxxxxuQ&cot=2 
33 = https://www.google.com/webhp?hl=en&sa=X&ved=0ahUKxxxxxy8-rSAxxxxxxxx8QPAgD 
34 = https://support.google.com/websearch/answer/186645?hl=en 
35 = https://www.google.com/intl/en/policies/privacy/?fg=1 
36 = https://www.google.com/intl/en/policies/terms/?fg=1 
37 = https://www.google.com/preferences?hl=en 
38 = https://www.google.com/preferences?hl=en&fg=1 
39 = https://www.google.com/advanced_search?hl=en&fg=1 
40 = https://www.google.com/history/optout?hl=en&fg=1 
41 = https://support.google.com/websearch/?p=ws_results_help&hl=en&fg=1 
------------------ (removed) 
43 = https://www.google.com/intl/en/ads/?fg=1 
44 = https://www.google.com/services/?fg=1 
45 = https://www.google.com/intl/en/about.html?fg=1 

Answer 1

如果你真的需要得到以「href」屬性的所有元素，除了這2個鏈接，那麼你可以使用未來的XPath：

//*[@href][not(contains(@href,'javascript:void'))] 

Answer 2

如果你想獲得一個包含URL作爲參考錨，你可以使用下面XPath表達：

"//a[starts-with(@href, 'http')]" 

這應包括URLs既http和https模式