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I am trying to delete an object's property but the property does not get deleted at all...

What I have:

var tagFound = yield tags.findById(this.params.tagId);
debug('prior delete: %j', tagFound);
delete tagFound.password;
debug('after delete: %j', tagFound);

What I get:

api_v1 prior delete: {"_id":"55e064e9727b44c32a262c0f","expires":"2015-08-29T13:40:57.673Z","password":"$2a$08$hucJyHIU5gholAB1L.wVKeFoTmvFho9xFiJAAvmwmtKphLuJ9Hq4K","type":"free","name":"teste","__v":0,"visible":true,"locations":[{"latitude":65.9667,"longitude":-18.5333,"_id":"55e064e9727b44c32a262c10","timestamp":"2015-08-28T13:40:57.572Z"}]}

api_v1 after delete: {"_id":"55e064e9727b44c32a262c0f","expires":"2015-08-29T13:40:57.673Z","password":"$2a$08$hucJyHIU5gholAB1L.wVKeFoTmvFho9xFiJAAvmwmtKphLuJ9Hq4K","type":"free","name":"teste","__v":0,"visible":true,"locations":[{"latitude":65.9667,"longitude":-18.5333,"_id":"55e064e9727b44c32a262c10","timestamp":"2015-08-28T13:40:57.572Z"}]}

Maybe my eyes are too tired, but I simply cannot figure this out, does anybody see something obvious that I am missing here?

Update: I put this into http://jsfiddle.net/fc8mohwp/, the problem is, it is working there, but not here (iojs). Should there be any difference?

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5
  • 1
    what does delete return? Commented Aug 28, 2015 at 14:09
  • 1
    Where does tagFound come from? If the password field comes from a HTML-Tag than it cannot be deleted. Only user defined properties can be deleted. At least that's the case in a browser but probably something similar is happening in node. Commented Aug 28, 2015 at 14:09
  • Delete returns true. tagFound comes from a mongoDB document Commented Aug 28, 2015 at 14:14
  • The object property may not be writable. Commented Aug 28, 2015 at 14:16
  • please remove node.js tag and insert io.js Commented Aug 28, 2015 at 14:18

3 Answers 3

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4

Certain variables cannot be deleted depending on the context of how they are declared. For example, you can't delete variables that have been defined in a global scope.

I hate to post a link answer, but this blog post describes all the rules and edge cases with using delete. It is quite a bit for me to include in a SO post

Using delete in Javascript

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5 Comments

tagFound is declared locally, but it comes from an yield statement, could that be the problem?
@rbaprado Possible. Where is tags.findById coming from? Is this a DOM element that your trying to delete?
tags.findById is a wrapper for mongoose's findOne, no DOM here
@rbaprado Gotcha. Hard to say then. The mongoose library might be doing something goofy to try and protect it's objects. You could try doing a deep copy of the object by converting it to and from a JSON string. That might allow you to declare a local copy of the variable which would allow you to delete it.
As ugly as it gets, tagFound = JSON.parse(JSON.stringify(mobtagFound)) did the trick, thanks!
1

This can have multiple reasons for example the password field can't be changed or the password field is coming from the prototype chain.

You can debug this with Object.getOwnPropertyDescriptor(tagFound, 'password');

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1 Comment

Then it is coming from the prototype.
-3

You can delete a property from a javascript object by using the delete operator

delete myObject.proportyname;

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1 Comment

delete is an operator, not a function. Therefore this should be delete myObject.propertyname

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