Object.prototype. Hasownproperty() and in

hasOwnProperty()  All inherited  Object  All of the objects will inherit to  hasOwnProperty  Method . This method can be used to detect whether an object contains specific attributes of itself ; and  in  Operators are different , This method ignores the properties inherited from the prototype chain .
 

in The operator : Detect specified objects ( On the right ) Whether there is a corresponding attribute value on the prototype chain . 

hasOwnProperty Method : Detect whether there is a corresponding attribute value on the specified object .

 The difference between the two is in Will find the prototype chain , and hasOwnProperty Can't 

hasOwnProperty() grammar

obj.hasOwnProperty(prop)

Parameters ：prop Of the attribute to be detected  String  Name in string form , perhaps  Symbol.

Return value ： Boolean value used to determine whether an object contains a specified attribute  Boolean. This method Can't Check whether the attribute exists in the prototype chain of the object , This attribute is only an object In itself Only one member of will return true

Example

Object.prototype.bar = {bar:'object prototype'}; 
var foo = {
    goo: undefined
};
console.log('bar' in foo);// expected output: true(in Will find the prototype chain )
console.log(foo.hasOwnProperty('bar'));// expected output: false
console.log(foo.hasOwnProperty('goo'));// expected output: true