jquery 学习之二 属性相关

attr(name) 取得第一个匹配元素的属性值。通过这个方法可以方便地从第一个匹配元素中获取一个属性的值。如果元素没有相应属性,则返回 undefined 。 Access a property on the first matched element. This method makes it easy to retrieve a property value from the first matched element. If the element does not have an attribute with such a name, undefined is returned. 返