Question

I’m using PHP to json encode a massive multi-dimensional array of events, so i get something like this:

var ents = {"7":{"event_id":"7","nn":"The Whisky Drifters","nn_url":"the-whisky-drifters",
  "venue":"The Grain Barge","date_num":"2010-06-11","date_txt":"Friday 11th June",
  "gig_club":"1","sd":"A New Acoustic String Band...","ven_id":"44",
  "art":0},"15":{"event_id":"15","nn":"Bass Kitchen","nn_url":"bass-kitchen",
  "venue":"Timbuk2","date_num":"2010-06-11","date_txt":"Friday 11th June",
  "gig_club":"2","sd":"Hexadecimal \/ DJ Derek \/ Id","ven_id":"21",
  "art":1},

the first dimension is the id, see

var ents = {"7":{

So it’s possible to get the ids without examining the nested objects…

What’s the fastest, most efficient way to check if my JSON contains an id?

Answer 1

You can use the hasOwnProperty method:

if (ents.hasOwnProperty('7')) {
  //..
}

This method checks if the object contains the specified property regardless of its value.

Is faster than the in operator because it doesn’t checks for inherited properties.