double slash for xpath. Selenium Java Webdriver

问题

I am using Selenium WebDriver. I have a doubt about the xpath.

If I have the following code example:

<div>
     <div>
           <div>
                 <a>
                      <div>
                      </div>
                 </a>
           </div>
     </div>
</div>

And I want to locate the element which is in the last <div>. I think I have 2 options with the xpath.

First option is with single slash:

driver.findElement(By.xpath("/div/div/div/a/div")).click();

Second option is using double slash (and here is where I have the doubt).

driver.findElement(By.xpath("//a/div")).click();

Is it going to search in the <a> directly, but what happens if the html example code was just a part of a bigger code and in this bigger code are more "<a>"?. Where would this method look exactly?

What happens for example if I do it like this:

driver.findElement(By.xpath("//div")).click();

Would it looks if every <div> found in the html code?

回答1:

First of all, avoiding // is usually the right thing to do - so, the first expression you show is perfect.

Would it looks if every <div> found in the html code?

Yes, exactly. An XPath expression like

//div

will select all div elements in the document, regardless of where they are.

what happens if the html example code was just a part of a bigger code and in this bigger code are more <a>?. Where would this method look exactly?

Then, let us make the HTML "bigger":

<div>
     <a>
         <p>C</p>
     </a>
     <div>
           <div>
                 <a>
                      <div>A</div>
                 </a>
           </div>
           <a>
               <div>B</div>
           </a>
     </div>
</div>

As you can see, I have added two more a elements - only one of them contains a div element. Assuming this new document as the input, there will now be a difference between

/div/div/div/a/div

which will select only <div>A</div> as the result, and

//a/div

which will select both <div>A</div> and <div>B</div> - because the exact position of a in the tree is now irrelevant. But none of them will select the first a element that contains p.

来源：https://stackoverflow.com/questions/29938820/double-slash-for-xpath-selenium-java-webdriver

标签

html

selenium

xpath

selenium-webdriver