How to delete Javascript object property?

Question

I am trying to delete a object property which is shallow copy of another object. But the problem arises when I try to delete it, it never goes off while original value throws expected output.

var obj = {
 name:"Tom"
};
var newObj = Object.create(obj);
delete newObj.name;//It never works!
console.log(newObj.name);//name is still there

• Rayon: Both are completely different objects! Not referenced!
• Rayon: With var newObj = obj; It would work as you are expecting!
• Rayon: From docs, The Object.create() method creates a "new object"
• GameAlchemist: Notice that newObj has no name property, so your delete is useless on it. It is newObj's prototype === obj, which has the name property... or not if you deleted it...

Answer 1

newObj inherits from obj.

You can delete the property by accessing the parent object:

delete Object.getPrototypeOf(newObj).name;

(which changes the parent object)

You can also shadow it, by setting the value to undefined (for example):

newObj.name = undefined;

But you can't remove the property on newObj without deleting it from the parent object as the prototype is looked up the prototype chain until it is found.

• Rajaprabhu Aravindasamy: But usage of _proto_ is not recommended. Isn't it?
• Denys Séguret: I'm not sure there's really a notable difference when using it read only but yes it's the recommended practice now.
• fruitjs: Thanks Denys for the quick reply, it is working now.

Answer 2

Basically Object.create will create an object , set its prototype as per the passed object and it will return it. So if you want to delete any property from the returned object of Object.create, you have to access its prototype.

var obj = { name:"Tom" };
var newObj = Object.create(obj);
delete Object.getPrototypeOf(newObj).name
console.log(newObj.name); //undefined.

• manuell: In the Chrome console, the OP's code works fine: no need to use prototype.
• Rajaprabhu Aravindasamy: @manuell I am using chrome and it is not working as intended.
• manuell: You are right. I was running the delete obj.name; line, too. Without that one, name is still here in newObj (sort of), indeed.
• manuell: The downvote is not mine. I just upvoted, and the downvote is still here.
• Rajaprabhu Aravindasamy: @manuell Oh Thats's fine. keep encouraging our peers mate. :)