Find object's value

Question

Is there any not loop-based approach in JavaScript or JQuery that can check presence of some VALUE from object's properties. I mean here if I have

obj = { prop1:val, prop2:val2 }

is that possible with maybe one statement check is val2 presence among values of obj ?

UPDATE 1: The loop here is not the key! I can use loop if it is wrapped in some JQuery predefined function!

UPDATE 2: Writing a hand-made function is not so elegant, I think. I would like to find some library based solution for such a common and usual problem.

Short answer: no, you have to iterate over the object, or use a function that iterates over the object. — zzzzBov, Nov 30 '12 at 18:06
Depends what you are trying to do. Are you trying to test for the presence of a known property of an object in another? — Mike Bonds, Nov 30 '12 at 18:10
@zzzzBov what function do you mean? Just written by myself with for-loop for testing value presence? I would like to have more elegant solution — Michael Z, Nov 30 '12 at 18:14
@MichaelZ, you said "non loop-based approach" which is not possible as any function you might use to search would need to use a loop in one way or another. There are certainly elegant functions that exist so that you might call something along the lines of `contains(obj, val2)`, but in that case the `contains` function would be loop-based. — zzzzBov, Nov 30 '12 at 18:19
It should be noted that the "duplicate" referenced isn't a duplicate at all -- that one is asking to *search* the text in all keys, not match them. — McGarnagle, Nov 30 '12 at 22:15

Selvakumar Arumugam · Accepted Answer · 2012-11-30T18:33:42.837

4

No you cannot find if a value exist in an object in one statement without looping.

You can use native API or a library.. but they are going to internally loop thru all values.

The toll on any other method will be same as iterating the object.. So I would write a simple for loop to do it.

I would simply write this 4 line code in my script file and include that script file instead of including a library.. which would be the same. http://jsfiddle.net/sQW4P/2/ <-- Incase if you need such a function.

edited Nov 30 '12 at 18:33

answered Nov 30 '12 at 18:08

Selvakumar Arumugam

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The loop here is not the key! I can use loop if it is wrapped in some JQuery predefined function! – Michael Z Nov 30 '12 at 18:15
@MichaelZ, then you need to clarify your question. – zzzzBov Nov 30 '12 at 18:20
@MichaelZ I don't think there is any such function in jQuery. So if you worried about having the loop inside your webpage.. move it to script file, name it a function and call the function. I think it should be available in some other library.. but adding a new library for this is no good. – Selvakumar Arumugam Nov 30 '12 at 18:20
Writing a hand-made function is not so elegant, I think. I would like to find some library based solution for such a common and usual problem. – Michael Z Nov 30 '12 at 18:26
@MichaelZ In my opinion, writing hand-made 1000 line code is not so elegant.. but looking for a library to write a 4 line code is not my style. http://jsfiddle.net/sQW4P/2/ – Selvakumar Arumugam Nov 30 '12 at 18:32

Faiz · Answer 2 · 2012-11-30T18:24:58.267

1

This works with jQuery:

$.grep($.map(obj, function(v,k){return v}), function(el){return el == val2})

You could wrap it like so:

function hasVal(o, v) {
  $.grep($.map(o, function(v,k){return v}), function(el){return el == v}).length > 0
}

edited Nov 30 '12 at 18:24

answered Nov 30 '12 at 18:18

Faiz

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McGarnagle · Answer 3 · 2012-11-30T18:45:33.770

If you're ok using an external library, Underscore.js is fairly concise:

_.contains(_.values(obj), "val2");
// true

This is Underscore's values method:

Return all of the values of the object's properties.

Here is its implementation from the source code:

// Retrieve the values of an object's properties.
  _.values = function(obj) {
    var values = [];
    for (var key in obj) if (_.has(obj, key)) values.push(obj[key]);
    return values;
  };

As you can see, it just iterates over the keys in the object, and pushes them to an array. So, no, it's not possible to do this without an iteration.

David Hellsing · Answer 4 · 2012-11-30T18:34:36.053

0

The only way I can think of is JSON:

new RegExp(':\"'+val+'\"').test(JSON.stringify(obj))

Demo: http://jsfiddle.net/J4TDS/

If you are fine with using a function, no need to look in libs, it’s only a few bytes:

function find(o, v) {
    for(var i in o) {
        if (o[i] === v) return true;
    }
}

find(obj, val2);

edited Nov 30 '12 at 18:34

answered Nov 30 '12 at 18:11

David Hellsing

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Doesn't this hide some loops inside the RegExp? – Almo Nov 30 '12 at 18:14
@David, a regex has a loop to scan through the string. AND, JSON.stringify loops through the object to build the string. This has multiple loops. – jfriend00 Nov 30 '12 at 18:17
@David Hmmm, you have a nice solution. It doesn't matter for me if it inner implementation has loops! – Michael Z Nov 30 '12 at 18:20
@MichaelZ if you are fine with writing a function that loops, then you should do that instead. Using JSON comparison like this is not very safe – David Hellsing Nov 30 '12 at 18:21
@MichaelZ If you worried about having the loop inside in your webpage.. then move that code to script file, name it a function and call the function which is same as including a library and calling its function. – Selvakumar Arumugam Nov 30 '12 at 18:22
Writing a hand-made function is not so elegant, I think. I would like to find some library based solution for such a common and usual problem. – Michael Z Nov 30 '12 at 18:22

Find object's value

4 Answers4