up vote 11 down vote favorite
5

I have a multidimensional object (it's basically an array):

Object = { 1 : { name : bob , dinner : pizza }, 2 : { name : john , dinner : sushi }, 3 : { name : larry, dinner : hummus } }

I want to be able to search the object/array for where the key is "dinner", and see if it matches "sushi".

I know jQuery has $.inArray, but it doesn't seem to work on multidimensional arrays. Or maybe I'm wrong. indexOf also seems to only work on one array level.

Is there no function or existing code for this?

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This has been asked before. You have to write your own function or use some other library. – Felix Kling Mar 3 '11 at 13:47
Please note that Object is reserved in Javascript, Object is the object object, ie the mother of all objects. – adamse Mar 3 '11 at 14:15

3 Answers

up vote 30 down vote accepted

If you have an object like this

var peoples = [
  { "name": "bob", "dinner": "pizza" },
  { "name": "john", "dinner": "sushi" },
  { "name": "larry", "dinner": "hummus" }
];

Ignore what's below. Use the filter method!

peoples.filter(function (person) { return person.dinner == "sushi" });
  // => [{ "name": "john", "dinner": "sushi" }]

You can search for people who have "dinner": "sushi" using a map

peoples.map(function (person) {
  if (person.dinner == "sushi") {
    return person
  } else {
    return null
  }
}); // => [null, { "name": "john", "dinner": "sushi" }, null]

or a reduce

peoples.reduce(function (sushiPeople, person) {
  if (person.dinner == "sushi") {
    return sushiPeople.concat(person);
  } else {
    return sushiPeople
  }
}, []); // => [{ "name": "john", "dinner": "sushi" }]

I'm sure you are able to generalize this to arbitrary keys and values!

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1  
Just keep in mind that these solutions are part of ECMAScript 5 and not supported in IE8. kangax.github.com/es5-compat-table As much as I prefer @adamse's answer, alex's is more "old shitty browser" friendly. Not sure about performance though. – EasyCo Sep 25 '12 at 5:46
@SalmanA - nor the question or the solution is referring to jQuery. The javascript filter() is used, not jQuery-specific $.filter() - tutorialspoint.com/javascript/array_filter.htm – Tapirboy Jan 14 at 14:14
As mentioned by EasyCo, the filter function is not supported in IE8. However, it is easily added to the Array prototype and thus usable in any browser with a small function at the beginning of your scripts. This is outlined in the filter documentation. It gives the exact function specified in ECMA-262, so it's literally the same thing. – dallin yesterday
up vote 2 down vote 
var getKeyByDinner = function(obj, dinner) {
    var returnKey = -1;

    $.each(obj, function(key, info) {
        if (info.dinner == dinner) {
           returnKey = key;
           return false; 
        };   
    });

    return returnKey;       

}

jsFiddle.

So long as -1 isn't ever a valid key.

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up vote 1 down vote

If you're going to be doing this search frequently, consider changing the format of your object so dinner actually is a key. This is kind of like assigning a primary clustered key in a database table. So, for example: 

Object = { pizza : { name : bob }, sushi : { name : john } }

You can now easily access it like this: Object['sushi']['name']

Or if the object really is this simple (just 'name' in the object), you could just change it to:

Object = { pizza : bob, sushi : john }

And then access it like: Object['sushi'].

It's obviously not always possible or to your advantage to restructure your data object like this, but the point is, sometimes the the best answer is to consider whether your data object is structured the best way. Creating a key like this can be faster and create cleaner code.

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