JavaScript object learning experience summary_basic knowledge

1. Object creation method :
(1) Created through the new operator, new is followed by a constructor name
var object = new Object();
The constructor is called directly There is usually no return value, it just initializes the object passed in by this value; but when used with new, it returns an object value as the value of the new expression

(2) Object direct quantity
Object direct A quantity consists of a list of property descriptions enclosed in curly braces, where the property descriptions are separated by commas. Each attribute description of an object literal consists of the attribute name plus a colon and the attribute value. The attribute value can be of any type or a function
var object = { a : 1, b : 'a', c : function(){} }

2. Setting and querying object attributes
(1) Through dot operator object.p
(2) Array-like method object[ 'p']
Method 2 attributes are represented by strings, which can facilitate dynamic access to object attributes

3. Enumerate object attributes
for (p in object) {
// do something
}
p is an attribute of object. This method can only enumerate user-defined attributes, but cannot enumerate some predefined attributes and methods, such as constructor

4. Accessing undefined properties of the object returns undefined;

5. Object methods
The method definition and access of objects are similar to object properties, except that object methods are functions; in methods The object that calls the method is internally referenced through this

6. The prototype object of the object
(1) Each object has a prototype object, which inherits all the properties of its prototype object; properties Inheritance only occurs when the attribute value is read;
(2) The prototype of an object is defined by the constructor that creates and initializes the object;
(3) Each function (constructor) has A prototype attribute refers to the prototype object of the function