Which hooks are provided in jQuery?

问题

Officially only $.cssHooks is documented in jQuery API documentation, and $.valHooks is mentioned in a sentence for a workaround to a known issue in .val().

I wonder how many hooks are there in jQuery besides of these 2, and should we use $.valHooks in our plugin development? If so, I think it should be documented as a dedicated topic instead of one-sentence only.

回答1:

There are 8 different types of exposed hooks.

There is one more for internal usage only (which is exposed) - jQuery._queueHooks().

There are also two other hooks: nodeHook and boolHook which are used internally and their functionality is basically embedded into jQuery.attrHooks and jQuery.valHooks.

Here are the important ones:

jQuery.attrHooks
- Setting the type on a radio input after the value resets the value in IE6-9.
- Set contenteditable to false on removals (Bug #10429).
- Set width and height to auto instead of 0 on empty string (Bug #8150)
- Some attributes require a special call on IE - href, src, width and height.
- Return undefined in the case of empty string for the style attribute.
- Fix get/set for the value property in old IE
- When reading attribute values if no hook is defined it uses either boolHook or nodeHook (which is the same as jQuery.valHooks.button).
- Could be used to attach additional hooks when getting/setting an attribute of an element.
jQuery.propHooks
- href/src properties should get the full normalized URL (Bug #10299, Bug #12915).
- Fix for "Safari mis-reports the default selected property of an option".
- Could be used to attach additional hooks when getting/setting a property of an element.
jQuery.Tween.propHooks

jQuery.Tween is used for animations and such.
- Fix for scrollTop and scrollLeft in IE8 - will be removed in jQuery 2.0.
- Other animation stuff.
jQuery.cssHooks

Add in style property hooks for overriding the default behavior of getting and setting a style property.
- Fix for getting/setting the value of the CSS property opacity.
- Fix for getting witdth and height depending on the display property.
- Fix for setting width and height depending on the box-sizing property.
- Fix for getting margin-right.
- Fix for Webkit Bug #29084 - getComputedStyle returns percent when specified for top/left/bottom/right
- Used in jQuery.fn.animate to expand specified style properties like margin, padding and border.
- Used in other various jQuery.fn.animate related stuff.
- Setting various background CSS properties to inherit is achieved without using jQuery.cssHooks, because it is shorter this way.
- Could be used to attach additional hooks when getting/setting an individual style property of an element.
jQuery.valHooks
- Fixes a Blackberry 4.7 bug for option elements (Bug #6932).
- Used for reading selected value for select elements.
- Fixes reading some properties of the button element - id, name and coords. The same as nodeHook (see above).
- Fixes the incompatibility on checking radio and checkbox inputs between Webkit and others.
- Could be used to attach additional hooks when getting/setting the value of an input element.
jQuery.event.fixHooks

A holder for jQuery.event.mouseHooks and jQuery.event.keyHooks which require fixing and normalizing based on the support of the current browser.
jQuery.event.mouseHooks
- Used to transfer some properties from the original MouseEvent to the jQuery event object.
- Normalizes event.which (which mouse button was used) accross browsers, because event.button is not normalized.
- Calculates pageX, pageY, clientX, clientY and others if missing and set them to the jQuery event object.
jQuery.event.keyHooks
- Used to transfer some properties from the original KeyboardEvent to the jQuery event object.
- Normalizes event.which (the character code of the button which was pressed) across browsers. In the original event it could be char, charCode, key or keyCode.

From the jQuery 1.9.1 source.

来源：https://stackoverflow.com/questions/15494498/which-hooks-are-provided-in-jquery

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