map() supports traversing arrays only. As of jQuery 1.6 it also traverses objects. – icramc. Dec 28 '12 at 22:46. ... <看更多>

each() on objects, aka associative arrays. Someday an object of mine may happen to have a member named 'length' with a value exactly zero. $. ... <看更多>

if (pid.length). causes a reference error in your script if pid is undefined . So, if you don't know that pid exists ahead of time, then you have to check ... ... <看更多>

This is a post on the _.size method that can be used to get the element length of an Array, or the key length of a plain old object in the event ... ... <看更多>

The length property is read/write property of an Array object. When the length property is set to zero, all elements of the array are automatically deleted. ... <看更多>