How does dot(.) in xpath to take multiple form in identifying an element and matching a text

问题

I have the below dom structure:

<h3 class="popover-title">
 <div class="popup-title">
   <div class="title-txt">Associated Elements&nbsp;&nbsp(5)</div>
 </div>
</h3>

I am trying to write an xpath which will identify the title "Associated Elements" under h3 tag.

When my xpath is

//div[contains(@class, popover)]//h3[contains(.,'Associated Elements')]

the element is identified.

However when my xpath is

//div[contains(@class, popover)]//h3[contains(text(),'Associated Elements')]

the element is not identified. As per my understanding the dot(.) is a replacement for text(), but then why does it not identify the element when I use the text() function.

However, for another dom structure:

<h3 class="popover-title">
   <a class="btn-popover" href="#">x</a>
   "Associated Elements"
</h3>

The xpath :

//div[contains(@class, popover)]//h3[contains(text(),'Associated Elements')]

&

//div[contains(@class, popover)]//h3[contains(.,'Associated Elements')]

works fine.

Can someone please explain the behaviour of dot(.) under both these scenarios?

Is there a better way to write an xpath that holds good for both the exmaples? Please suggest.

回答1:

As selenium is tagged so this answer would be based on xpath-1.0 and the associated XML Path Language (XPath) Version 1.0 specifications.

---

contains(string, string)

The function boolean contains(string, string) returns true if the first argument string contains the second argument string, and otherwise returns false. As an example:

//h3[contains(.,'Associated Elements')]

---

Text Nodes

Character data is grouped into text nodes. As much character data as possible is grouped into each text node. The string-value of a text node is the character data. A text node always has at least one character of data. In the below example, text() selects all text node children of the context node:

//h3[text()='Associated Elements']

In your usecase, within the HTML the text Associated Elements &nbsp(5) have   which is alternatively referred to as a fixed space or hard space, NBSP (non-breaking space) used in programming to create a space in a line that cannot be broken by word wrap. Within HTML,   allows you to create multiple spaces that are visible on a web page and not only in the source code.

---

Analyzing your code trials

Your first code trial with:

//h3[contains(.,'Associated Elements')]

locates the element as it successfully identifies with partial text Associated Elements

Your second code trial with:

//h3[contains(text(),'Associated Elements')]

fails as the element contains some more characters e.g.   in addition to the text Associated Elements.

---

Reference

You can find a couple of relevant discussions in:

• How to locate the button element using Selenium through Python
• What does contains(., 'some text') refers to within xpath used in Selenium
• While fetching all links,Ignore logout link from the loop and continue navigation in selenium java

回答2:

The text() in contains(text(),'Associated Elements') is a selector that matches all of the text nodes that are children of the context node - it returns a node-set. That node-set is converted to string and passed to the contains() function.

text() isn't a function but a node test. It is used to select all text-node children of the context node. So, if the context node is an element named x, then text() selects all text-node children of x.

When you use contains(., 'Associated Elements') only an individual text node is passed to the function and it is able to uniquely match the text.

Note: copied and edited from this and this post.

来源：https://stackoverflow.com/questions/58114813/how-does-dot-in-xpath-to-take-multiple-form-in-identifying-an-element-and-mat