For/in looping through the properties of an object

the for/in statement loops through the properties of the object.
JS to get the key to get a corresponding value in an object method: Obj.key
There are two ways to get the corresponding value of an object in JS based on dynamic key:
var key = "Name1"; var value = Obj[key];
var key = "Name1"; var value = eval ("obj.") +key);

JS Code:

var obj={"name": "Wjy", "age": +, "sex": "Female" };//defines an object   var keys=[];//defines an array to accept the key  var values=[];//definition an array to accept value         for (var key in obj) {               keys.push (Key);               values.push (Obj[key]);//Acquired value                alert (eval ("obj.") +key));//Print value value           }  alert (obj.name) in a loop ;//wjy  alert ("KEYS IS :" +keys+ " AND VALUES IS :" +values);   Keys is : name,age,sex and values is : wjy,26,female 

1. When iterating through the properties of an object using the for In loop, the All properties on the prototype chain will be accessed :

object.prototype.bar = 10;//  Modify object.prototype  var obj={"name": "Wjy", "age": +, "sex": "female"};//define an object      var keys=[];//defines an array to accept key    var values=[];//to define an array to accept value       for (var key in obj) {         keys.push (key);         values.push (Obj[key]);//Acquired value           }    alert ("KEYS IS :" + Keys+ " AND VALUES IS :" +values);    //keys is : name,age,sex, bar and values is : wjy,26,female,10 

2. 

Function allpro (obj) {      var keys=[];        var values=[];        for (var key in  obj) {           //only iterates over the properties of the object itself, not the attributes inherited from the prototype chain.           if  (Obj.hasownproperty (key)  ===  true) {              keys.push (key);                 values.push ( Obj[key]);               }                           }      alert ("KEYS IS :" +keys+ "  and values is : "+valUES);    }  object.prototype.bar = 1;//  Modify object.prototype   var o={"name": "Wjy", "age": +, "sex": "female"};//define an object objects    allpro (o);   Keys is : name,age,sex and values is: wjy,26,female

Object objects do not have the length property, so they cannot be accessed directly through for (Var i=0;i<object.length;i++), and can be obtained by iterating over the length of the array that gets the key value to get the number of properties of the object itself.

keys.length;//"3"

For/in looping through the properties of an object