Prototype usage guide selector.js_prototype

Selector是利用css selector来匹配选择页面元素的，所以要理解Selector首先应该对css selector有所理解，下面是css2 selector的语法，当然很多浏览器只是支持其中的一部分，Prototype 中的Selector主要支持tag选择器、class选择器和id选择器，还有属性(attribute)选择器，基本上包含我们平时所用的所有类型

The following table summarizes CSS2 selector syntax, 详细的可以看http://www.w3.org/TR/REC-CSS2/selector.html:

Pattern	Meaning	Described in section
*	Matches any element.	Universal selector
E	Matches any E element (i.e., an element of type E).	Type selectors
E F	Matches any F element that is a descendant of an E element.	Descendant selectors
E > F	Matches any F element that is a child of an element E.	Child selectors
E:first-child	Matches element E when E is the first child of its parent.	The :first-child pseudo-class
E:link E:visited	Matches element E if E is the source anchor of a hyperlink of which the target is not yet visited (:link) or already visited (:visited).	The link pseudo-classes
E:active E:hover E:focus	Matches E during certain user actions.	The dynamic pseudo-classes
E:lang(c)	Matches element of type E if it is in (human) language c (the document language specifies how language is determined).	The :lang() pseudo-class
E + F	Matches any F element immediately preceded by an element E.	Adjacent selectors
E[foo]	Matches any E element with the “foo” attribute set (whatever the value).	Attribute selectors
E[foo=”warning”]	Matches any E element whose “foo” attribute value is exactly equal to “warning”.	Attribute selectors
E[foo~=”warning”]	Matches any E element whose “foo” attribute value is a list of space-separated values, one of which is exactly equal to “warning”.	Attribute selectors
E[lang|=”en”]	Matches any E element whose “lang” attribute has a hyphen-separated list of values beginning (from the left) with “en”.	Attribute selectors
DIV.warning	HTML only. The same as DIV[class~=”warning”].	Class selectors
E#myid	Matches any E element ID equal to “myid”.	ID selectors

Selector contains Selector objects and classes,

Selector object has the following two methods:

match(element): Whether the element matches this selector has been introduced in Element
findElements(parentNode): List of all descendant elements in parentNode that match this selector

The usage method is also very simple: var s=new Selector(expression); s.match(element); s.findElements($(element)), where expression can be as follows" div", "#id", ".class", "div#id", "div[attribute]", "div[attribute=fff]", "div[attribute!=sdf]"

Selector also has several static methods, they are:

matchElements(elements, expression): Returns a list of elements in elements that match expression
findElement(elements, expression, index): Returns elements The element with index index in the list of elements matching expression
findChildElements(element, expressions): Find the descendant elements of element A list of elements matching expressions, where expressions is an expression array, where expression supports the form of "div li.#id"

$$ method: Just simply call return Selector.findChildElements(document, $A(arguments))

Although Selector has so many methods, Most of them are called internally, and we rarely use them because we have a convenient method $$, which is enough for most situations.