我正在查看 jQuery 的源代码（特别是queue()函数），并看到它只是将函数放入.data()与该元素关联的对象中：
queue: function( elem, type, data ) {
var q;
if ( elem ) {
type = ( type || "fx" ) + "queue";
q = jQuery._data( elem, type );
// Speed up dequeue by getting out quickly if this is just a lookup
if ( data ) {
if ( !q || jQuery.isArray(data) ) {
q = jQuery._data( elem, type, jQuery.makeArray(data) );
} else {
q.push( data );
}
}
return q || [];
}
}
现在看看._datawhich is 只是.data()第四个参数 true，在哪里设置了计时器或动画？或者任何函数调用这个问题：
data: function( elem, name, data, pvt /* Internal Use Only */ ) {
if ( !jQuery.acceptData( elem ) ) {
return;
}
var privateCache, thisCache, ret,
internalKey = jQuery.expando,
getByName = typeof name === "string",
// We have to handle DOM nodes and JS objects differently because IE6-7
// can't GC object references properly across the DOM-JS boundary
isNode = elem.nodeType,
// Only DOM nodes need the global jQuery cache; JS object data is
// attached directly to the object so GC can occur automatically
cache = isNode ? jQuery.cache : elem,
// Only defining an ID for JS objects if its cache already exists allows
// the code to shortcut on the same path as a DOM node with no cache
id = isNode ? elem[ internalKey ] : elem[ internalKey ] && internalKey,
isEvents = name === "events";
// Avoid doing any more work than we need to when trying to get data on an
// object that has no data at all
if ( (!id || !cache[id] || (!isEvents && !pvt && !cache[id].data)) && getByName && data === undefined ) {
return;
}
if ( !id ) {
// Only DOM nodes need a new unique ID for each element since their data
// ends up in the global cache
if ( isNode ) {
elem[ internalKey ] = id = ++jQuery.uuid;
} else {
id = internalKey;
}
}
if ( !cache[ id ] ) {
cache[ id ] = {};
// Avoids exposing jQuery metadata on plain JS objects when the object
// is serialized using JSON.stringify
if ( !isNode ) {
cache[ id ].toJSON = jQuery.noop;
}
}
// An object can be passed to jQuery.data instead of a key/value pair; this gets
// shallow copied over onto the existing cache
if ( typeof name === "object" || typeof name === "function" ) {
if ( pvt ) {
cache[ id ] = jQuery.extend( cache[ id ], name );
} else {
cache[ id ].data = jQuery.extend( cache[ id ].data, name );
}
}
privateCache = thisCache = cache[ id ];
// jQuery data() is stored in a separate object inside the object's internal data
// cache in order to avoid key collisions between internal data and user-defined
// data.
if ( !pvt ) {
if ( !thisCache.data ) {
thisCache.data = {};
}
thisCache = thisCache.data;
}
if ( data !== undefined ) {
thisCache[ jQuery.camelCase( name ) ] = data;
}
// Users should not attempt to inspect the internal events object using jQuery.data,
// it is undocumented and subject to change. But does anyone listen? No.
if ( isEvents && !thisCache[ name ] ) {
return privateCache.events;
}
// Check for both converted-to-camel and non-converted data property names
// If a data property was specified
if ( getByName ) {
// First Try to find as-is property data
ret = thisCache[ name ];
// Test for null|undefined property data
if ( ret == null ) {
// Try to find the camelCased property
ret = thisCache[ jQuery.camelCase( name ) ];
}
} else {
ret = thisCache;
}
return ret;
}
编辑zzzzBov：
animate: function( prop, speed, easing, callback ) {
var optall = jQuery.speed( speed, easing, callback );
if ( jQuery.isEmptyObject( prop ) ) {
return this.each( optall.complete, [ false ] );
....
return optall.queue === false ?
this.each( doAnimation ) :
this.queue( optall.queue, doAnimation );