"JS" for In loop object, function of hasOwnProperty ()

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 var  obj = {name:  "  echolun   "  "  24   " , sex:  "  Span style= "COLOR: #800000" >male   " },  objname  =[], //  used to load object property name  objval=[]; //  for  (var  i in      obj) {objname.push (i); Objval.push (Obj[i]);} Console.log (objname,objval);  

It is important to note that the for In loop object accesses all object properties on the prototype chain, see below.

varobj ={name:"Echolun", Age:" -", Sex:"male"},objname=[],//used to load object property namesObjval=[];//used to load object property valuesObject.prototype.game="lastGAME"; for(varIinchobj)    {Objname.push (i); Objval.push (Obj[i]);} Console.log (Objname,objval);}

This is also the loop object, obj, but it is important to note that the game of the additional objects we added on the prototype chain is also being recycled.

So we just want to loop the corresponding object what to do, here the hasOwnProperty () method is introduced, andthe hasOwnProperty () function is used to indicate an object itself ( excluding the prototype chain ) Whether the property has the specified name. Returns true if any, otherwise false is returned.

To put it simply, it can help you point to your current loop and filter out other objects on the prototype chain, because it's very hard to make sure that someone else modifies the prototype chain, which is more secure, and then modifies the code.

varobj ={name:"Echolun", Age:" -", Sex:"male"},objname=[],//used to load object property namesObjval=[];//used to load object property valuesObject.prototype.game="lastGAME"; for(varIinchobj) {    if(Obj.hasownproperty (i)) {Objname.push (i);    Objval.push (Obj[i]); }}console.log (Objname,objval);}

See, this will filter out the game.

"JS" for In loop object, function of hasOwnProperty ()