DocumentFromUrl builds a goquery.Document from urlRef.

HtmlNodeGrepAttr greps value of given attrName with reg.

NodeContainsText checks whether node contains text.

NodeGrepAllHref greps all href inside node and its children.

NodeGrepHref greps a href link that matches regexp in node.

NodeSearchAttr searches html node, find attr's value and return.

NodeSearchAttrEq searches html node, find attr's value equal to attrValue in node.