什么是 。 属性位置的xpath中的（点）？

Question

At some places, I saw element like following -

//a[.='Assignment']

Generally we've syntax like - //tagName[attributeKey='attributeValue'] or //tagName[text()='textValue']

But what is intention of . in xpath //a[.='Assignment'] ?

Answer 1

I'll use XPath 2.0 terminology here: XPath 1.0 has different terminology but the effect of the expression is the same.

"." refers to the context item: that is, the a element that you are testing against the predicate. Its value here is a node. When a node is used as an argument of "=", it is atomized , which means (unless your code is schema-aware, which is unlikely) that the string value of the node is compared with the other operand of "=". The string value of an element is the concatenation of all its descendant text nodes.

It sounds like you don't have ready access to an XPath reference. There are quite a few good books that cover XPath, there are online tutorials (which are highly variable in quality) and the W3C specification itself (especially for XPath 1.0) is surprisingly easy reading.