What is the class array of objects

In javascript, a special object is an array, which array property called positive, and the increase or decrease in length property change occurs array members, while some methods inherited array for operation and from arry constructor and for a common object, if it's all the property names are positive integers, colleagues have the appropriate length property, so although the object is not created by the array constructor, which still presents an array of behavior, in this case, these objects are referred to as "array-like object"
such as:
var O = {0: 42.1: 52,2: 63 is, length:. 3}
the console.log (0);
and the general objects of different is an array of objects have a characteristic type: application of the method can operate on an array of an array of class Object.