What is the XPath expression to find only the first occurrence?

Question

I used this Xpath expression \"//span[@class=\'Big\']\" and got all elements in that page that are under tag and class=\'Big\'

Answer 1

The correct answer (note the brackets):

(//span[@class='Big'])[1]

The following expression is wrong in the general case:

//span[@class='Big'][1]

because it selects every span element in the document, that satisfies the condition in the first predicate, and that is the first such child of its parent -- there can be many such elements in an XML document and all of them will be selected.

For more detailed explanation see: https://stackoverflow.com/a/5818966/36305