If double slash (//) is used 2 times in XPath, what does it mean?

A double slash "//" means any descendant node of the current node in the HTML tree which matches the locator.

A single slash "/" means a node which is a direct child of the current.

//div[@id='add']//span[@id=addone'] will match:

<div id="add">  <div>    <span id="addone">  </div></div>

And:

<div id="add">    <span id="addone"></div>

//div[@id='add']/span[@id=addone'] will match only the second HTML tree.

xml selenium selenium-webdriver xpath

Double slash (//) is the descendant-or-self axis; it is short for /descendant-or-self::node()/.

In your example XPath:

//div[@id='add']//span[@id='addone']

The first time // appears, it selects all div elements in thedocument with an id attribute value equal to 'add'.
The second time // appears, it selects all span elements that aredescendents of each of the div elements selected previously.
Note that using two double slashes twice is different than just usingdouble slash once. For example, //span[@id='addone'] would selectall span elements with @id='addone' in the entire document, regardless of whether they are a descendent of a div with @id='add'.

xml selenium selenium-webdriver xpath

If you'd have this:

<div id='add'>   <ul>      <li>        <span id='add one' />      </li>   </ul></div>

Then

//div[@id='add']//span[@id='addone']

will result in the span because the second // means you look for any child relative to

div[@id='add']

that is span[@id='add one'].

If you'd use one slash

//div[@id='add']/span[@id='addone']

then of course you won't find it because then you look for a direct child and you'd have to use

//div[@id='add']/ul/li/span[@id='addone']

So the second // is very useful in avoiding extra hierarchy in your XPaths.

CodeHunter