Underscore, check if key exists in array of objects

Question

I am trying to check new data I am receiving against an object I am holding onto, and what I am trying to find out is if they key of the object I am being send matches any keys in the object I currently have.

So I am holding onto an object like

myObj = [{"one": 1}, {"two": 2 },{"three" : 3}];

And I get sent a single object like

{"three" : 5 }

And I want to just check this object against the array of objects (myObj) and see if there is anything with the key "three" inside of it ( I don't care about the values, just the key matching) so I can pop it into an if statement to separate like -

if( array of objects (myObj) has key from single object ( "three" ) ) {}

I am using underscore. Thanks!

Edit : Sorry this was not clear, I am editing it to clarify -

I am holding onto myObj (the array of objects), and being sent a single object - the "three" for example, and I just want to pull that single object key out (Object.keys(updatedObject)[0]) and check if any of the objects in the object array have that key.

So _has seems like it is just for checking a single object, not an array of objects.

possible duplicate of Check if a key exists inside a json object — Sergiu Paraschiv
– Sergiu Paraschiv, Commented Mar 3, 2015 at 15:38
Google "javascript check if key exists in object" returns three relevant results. — Sergiu Paraschiv
– Sergiu Paraschiv, Commented Mar 3, 2015 at 15:38
@SergiuParaschiv: not a duplicate at all. Its underscore.js — codeandcloud
– codeandcloud, Commented Mar 3, 2015 at 15:40
Not a duplicate, this regards using underscore, maybe we should remove the javascript tag to avoid confusion — Dexygen
– Dexygen, Commented Mar 3, 2015 at 15:44
The only reason anyone would use anything other than hasOwnProperty would be browser support, right? — Sergiu Paraschiv
– Sergiu Paraschiv, Commented Mar 3, 2015 at 17:32

Bergi · Accepted Answer · 2015-03-03 16:37:29Z

13

You're looking for the _.some iterator combined with a callback that uses _.has:

if (_.some(myObj, function(o) { return _.has(o, "three"); })) {
    …
}

answered Mar 3, 2015 at 16:37

Bergi

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Serhii Kozachenko · Accepted Answer · 2015-03-03 15:39:22Z

10

You can use underscore method 'has'

Here the example:

_.has({"three" : 5 }, "three");
=> true

From the underscore doc:

Does the object contain the given key? Identical to object.hasOwnProperty(key), but uses a safe reference to the hasOwnProperty function, in case it's been overridden accidentally.

answered Mar 3, 2015 at 15:39

Serhii Kozachenko

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1 Comment

ajmajmajma Over a year ago

This is on the right track - however it is not checking if the array of objects has "three".

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