// Own properties are enumerated firstly, so to speed up,
// if last one is own, then all properties are own.
var key
for ( key in obj ) {}
return key === undefined || hasOwn.call( obj, key );
它这里说如果一个对象的最后一个属性是实例自己的属性,那么所有的属性都是实例自己的属性。这对低版本浏览器来说应该是不对的。所以jquery后来又加了如下代码修复:
复制代码
// Support: IE<9
// Handle iteration over inherited properties before own properties.
if ( support.ownLast ) {
for ( key in obj ) {
return hasOwn.call( obj, key );