CODEWITHSUNDEEP
javascript
jofftiquez
jofftiquez

Reputation: 7708

javascript delete keyword not working properly

This is really weird I think, I have this json being sent through http. 

{
   "foo":"bar",
   "foo2":"bar2",
   "name":{
       "firstName":"Joff",
       "middleName":"Ramirez",
       "lastName":"Tiquez"
   }
}

On the server I was performing these commands:

var data = req.body; // the json from http
console.log('data', data); // the data now has the req.body's value 
delete data.name; // <-- here's the delete
console.log('data', data); // the name object will obviously be deleted
console.log('req.body', req.body); // the name on the req.body was deleted too. Wtf?

So when I tried to use the req.body.name on the other parts of my program, the name is now gone. Is that how delete is supposed to work?

Upvotes: 2

Views: 1781

Answers (4)

Mohan P
Mohan P

Reputation: 422

You need to save data in other variable 1 by 1 object if you want to delete in same way.

Because when you use any object to assign in other object then value assign by reference. for more please check- this link

For your problem solution put values 1 by 1.

Upvotes: 2

Thalaivar
Thalaivar

Reputation: 23622

var data = JSON.parse(JSON.stringify(req.body));
delete data.name; // <-- here's the delete

Now when you do a 

console.log('req.body', req.body); // This won't be deleted.

As pointed out by @Dellirium, Objects are passed by reference, reqBody is the same object as the data

Upvotes: 6

Quentin
Quentin

Reputation: 943150

Is that how delete is supposed to work?

Yes. delete deletes properties from objects.

… but that isn't where your confusion is coming from.

var data = req.body;

The assignment operator copies the value of req.body and that value is a reference to an object (JS only ever gives you a reference to an object to play with).

When you copy that reference to data you have two references pointing to the same object. When you delete a property from the object, it is removed from the object and it doesn't matter which reference to that object you use.

See this question for some information about making a deep copy of an object.

Upvotes: 3

Doruk
Doruk

Reputation: 914

Yes it is. Delete keyword deletes the property of the instance itself.

EDIT: Objects are passed by reference. Consider copying the object, so the changes you do will only affect the object you're changing.

Upvotes: 1

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