JavaScript - how to check if Object has a certain key, when key is variable?

Question

Example:

var o = {'key': 'value'};
var key = 'key';
console.log('key' in o); //true
console.log(key in o); //false

How to do this? =)

The second log is true as well. Providing a string literal directly or a variable containing a string value has the same effect. — Šime Vidas
– Šime Vidas, Commented Jul 6, 2013 at 19:27
Lol actually I made this post by mistake - @amadeus is right =) — Gill Bates
– Gill Bates, Commented Jul 6, 2013 at 20:09

David Thomas · Accepted Answer · 2013-07-06 19:23:56Z

5

I'd suggest:

o.hasOwnProperty(key);

JS Fiddle demo.

References:

hasOwnProperty().

answered Jul 6, 2013 at 19:23

David Thomas

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3 Comments

David Thomas Over a year ago

I am an evil ninja... ;)

Wolfgang Kuehn Over a year ago

And what exactly does this answer?

David Thomas Over a year ago

I was under the impression that this answered the question: 'how [can I] check if Object has a certain key, when [that] key is [a] variable?' Does it not?

Jordan Sitkin · Accepted Answer · 2013-07-06 19:24:01Z

3

Try hasOwnProperty:

o.hasOwnProperty(key);

answered Jul 6, 2013 at 19:24

Jordan Sitkin

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