CODEWITHSUNDEEP
javascriptloops
dzm
dzm

Reputation: 23574

Deleting property from object in javascript

I'm looping through an object in javascript and deleting an item that is undefined, using:

for (var key in result) {
  if (result.hasOwnProperty(key)) {
     var obj = result[key];
     if (typeof obj.name === 'undefined') {
        delete result[key];
     }
  }
}

If I don't use the delete , this iterates just fine. However, when I use delete, I then get the error, 'TypeError: Cannot read property 'name' of undefined'

Any idea what I'm doing wrong here?

Thank you

EDIT: The object being iterated:

{
  date: Mon, 02 Apr 2012 17: 48: 17 GMT,
  t_date: Mon, 02 Apr 2012 17: 48: 17 GMT,
  start: 0,
  _id: 4f79e661d7cb8ccc1f000005
} {
  date: Mon,n02 Apr 2012 17: 48: 26 GMT,
  t_date: Mon, 02 Apr 2012 17: 48: 26 GMT,
  start: 0,
  _id: 4f79e66ad7cb8ccc1f000006
} {
  name: 'testname',
  date: Mon, 02 Apr 2012 17: 48: 29 GMT,
  t_date: Mon, 02 Apr 2012 17: 48: 29 GMT,
  start: 0,
  _id: 4f79e66dd7cb8ccc1f000007
}

Upvotes: 1

Views: 264

Answers (2)

Andrew Ferrier
Andrew Ferrier

Reputation: 17822

I'm not 100% sure why you're using the typeof operator there, but I think you can simplify the if statement to simply:

if(obj === undefined)

I also think the hasOwnProperty check is redundant, not sure what you are checking for there.

I've created an example to demonstrate this here: http://jsfiddle.net/andrewferrier/RxTF8/ (just use your browser console to see the resultant object).

Upvotes: -1

Eugene Retunsky
Eugene Retunsky

Reputation: 13139

It means that obj is undefined and therefore obj.name causes this error.

It should be:

 var obj = result[key];
 if (obj && typeof obj.name === 'undefined') {
    delete result[key];
 }

Upvotes: 6

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