Selector expressions in jQuery

注：本文内容摘录自《Learning jQuery (4th Edition)》。

The jQuery factory function $() is used to find elements on the page to work with. This function takes a string composed of CSS-like syntax, called a selector expression.

Simple CSS

Selector	Matches
`*`	All elements.
`#id`	The element with the given ID.
`element`	All elements of the given type.
`.class`	All elements with the given class.
`a, b`	Elements that are matched by a or b.
`a b`	Elements b that are descendants of a.
`a > b`	Elements b that are children of a.
`a + b`	Elements b that immediately follow a.
`a ~ b`	Elements b that are siblings of a and follow a.

Position among siblings

Selector	Matches
`:nth-child(index)`	Elements that are the index child of their parent element (1-based).
`:nth-child(even)`	Elements that are an even child of their parent element (1-based).
`:nth-child(odd)`	Elements which are an odd child of their parent element (1-based).
`:nth-child(formula)`	Elements that are the nth child of their parent element (1-based). Formulas are of the form an+b for integers a and b.
`:nth-last-child()`	The same as `:nth-child()`, but counting from the last element to the first.
`:first-child`	Elements that are the first child of their parent.
`:last-child`	Elements that are the last child of their parent.
`:only-child`	Elements that are the only child of their parent.
`:nth-of-type()`	The same as `:nth-child()`, but only counting elements of the same element name.
`:nth-last-of-type()`	The same as `:nth-last-child()`, but only counting elements of the same element name.
`:first-of-type`	Elements which are the first child of the same element name among their siblings.
`:last-of-type`	Elements which are the last child of the same element name among their siblings.
`:only-of-type`	Elements that are the only child of the same element name among their siblings.

Position among matched elements

Selector	Matches
`:first`	The first element in the result set.
`:last`	The last element in the result set.
`:not(a)`	All elements in the result set that are not matched by a.
`:even`	Even elements in the result set (0-based).
`:odd`	Odd elements in the result set (0-based).
`:eq(index)`	A numbered element in the result set (0-based).
`:gt(index)`	All elements in the result set after (greater than) the given index (0-based).
`:lt(index)`	All elements in the result set before (less than) the given index (0-based).

Attributes

Selector	Matches
`[attr]`	Elements that have the attribute attr.
`[attr="value"]`	Elements whose attr attribute is value.
`[attr!="value"]`	Elements whose attr attribute is not value.
`[attr^="value"]`	Elements whose attr attribute begins with value.
`[attr$="value"]`	Elements whose attr attributes ends with value.
`[attr*="value"]`	Elements whose attr attribute contains the substring value.
`[attr~="value"]`	Elements whose attr attribute is a space-delimited set of strings, one of which is value.
`[attr\|="value"]`	Elements whose attr attributes is either equal to value or begins with value followed by a hyphen.

Forms

Selector	Matches
`:input`	All `<input>`, `<select>`, `<textarea>`, and `<button>` elements.
`:text`	The `<input>` elements with type="text".
`:password`	The `<input>` elements with type="password".
`:file`	The `<input>` elements with type="file".
`:radio`	The `<input>` elements with type="radio".
`:checkbox`	The `<input>` elements with type="checkbox".
`:submit`	The `<input>` elements with type="submit".
`:image`	The `<input>` elements with type="image".
`:reset`	The `<input>` elements with type="reset".
`:button`	The `<input>` elements with type="button" and `<button>` elements.
`:enabled`	Enabled form elements.
`:disabled`	Disabled form elements.
`:checked`	Checked checkboxes and radio buttons.
`:selected`	Selected `<option>` elements.

Miscellaneous selectors

Selector	Matches
`:root`	The root element of the document.
`:header`	Header elements (for example, `<h1>`, `<h2>`).
`:animated`	Elements with an animation in progress.
`:contains(text)`	Elements containing the given text.
`:empty`	Elements with no child nodes.
`:has(a)`	Elements containing a descendant element matching a.
`:parent`	Elements that have child nodes.
`:hidden`	Elements that are hidden, either through CSS or because they are .
`:visible`	The inverse of `:hidden`.
`:focus`	The elements that has the keyboard focus.
`:lang(language)`	Elements with the given language code (either due to a lang attribute on the element or an ancestor, or a `<meta>` declaration).
`:target`	Whichever element is targeted by the URI's fragment identifier, if any.