Another solution is to create a lookup object:

var lookup = {};
for (var i = 0, len = array.length; i < len; i++) {
    lookup[array[i].id] = array[i];
}

... now you can use lookup[id]...

This is especially interesting if you need to do many lookups.

This won't need much more memory since the IDs and objects will be shared.

Underscore.js has a nice method for that:

myArray = [{'id':'73','foo':'bar'},{'id':'45','foo':'bar'},etc.]
obj = _.find(myArray, function(obj) { return obj.id == '45' })

I think the easiest way would be the following, but it won't work on Internet Explorer 8 (or earlier):

var result = myArray.filter(function(v) {
    return v.id === '45'; // Filter out the appropriate one
})[0].foo; // Get result and access the foo property

myArray.find(x => x.id === '45').foo

From MDN:

The find() method returns a value in the array, if an element in the array satisfies the provided testing function. Otherwise undefined is returned.

If you want to get array of matching elements, use filter() method instead:

myArray.filter(x => x.id === '45')

This will return array of objects. If you want to get array of foo properties, you can do this with map() method:

myArray.filter(x => x.id === '45').map(x => x.foo)

Side note: methods like find() or filter(), and arrow functions are not supported by all browsers, but it doesn't mean that you can't use these features right now. Just use Babel—it transforms ES6 code into ES5.

ECMAScript 6 provides the find-method on arrays. On your example, you’d use it like so:

myArray.find(function (d) {
    return d.id === 45;
}).foo;

// bar

It works without external libraries. But if you want older browser support you might want to include this polyfill.

Try the following

function findById(source, id) {
  for (var i = 0; i < source.length; i++) {
    if (source[i].id === id) {
      return source[i];
    }
  }
  throw "Couldn't find object with id: " + id;
}

myArray.filter(function(a){ return a.id == some_id_you_want })[0]

A generic and more flexible version of the findById function above:

// array = [{key:value},{key:value}]
function objectFindByKey(array, key, value) {
    for (var i = 0; i < array.length; i++) {
        if (array[i][key] === value) {
            return array[i];
        }
    }
    return null;
}

var array = [{'id':'73','foo':'bar'},{'id':'45','foo':'bar'}];
var result_obj = objectFindByKey(array, 'id', '45');

You can use filters,

  function getById(id, myArray) {
    return myArray.filter(function(obj) {
      if(obj.id == id) {
        return obj 
      }
    })[0]
  }

get_my_obj = getById(73, myArray);

You can get this easily using the map() function:

myArray = [{'id':'73','foo':'bar'},{'id':'45','foo':'bar'}];

var found = $.map(myArray, function(val) {
    return val.id == 45 ? val.foo : null;
});

//found[0] == "bar";

Working example: http://jsfiddle.net/hunter/Pxaua/

Using native Array.reduce

var array = [ {'id':'73' ,'foo':'bar'} , {'id':'45' ,'foo':'bar'} , ];
var id = 73;

var found = array.reduce(function(a, b){
    return (a.id==id && a) || (b.id == id && b)
});

returns the object element if found, otherwise false

While there are many correct answers here, many of them do not address the fact that this is an unnecessarily expensive operation if done more than once. In an extreme case this could be the cause of real performance problems.

In the real world, if you are processing a lot of items and performance is a concern it's much faster to initially build a lookup:

var items = [{'id':'73','foo':'bar'},{'id':'45','foo':'bar'}];

var lookup = items.reduce((o,i)=>o[i.id]=o,{});

you can then get at items in fixed time like this :

var bar = o[id];

You might also consider using a Map instead of an object as the lookup: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Map

You can do this even in pure JavaScript by using the in built "filter" function for arrays:

Array.prototype.filterObjects = function(key, value) {
    return this.filter(function(x) { return x[key] === value; })
}

So now simply pass "id" in place of key and "45" in place of value, and you will get the full object matching an id of 45. So that would be,

myArr.filterObjects("id", "45");

You may try out Sugarjs from http://sugarjs.com/.

It has a very sweet method on Arrays, .find. So you can find an element like this:

array.find( {id: 75} );

You may also pass an object with more properties to it to add another "where-clause".

Note that Sugarjs extends native objects, and some people consider this very evil...

Building on the accepted answer:

jQuery:

var foo = $.grep(myArray, function(e){ return e.id === foo_id})
myArray.pop(foo)

Or CoffeeScript:

foo = $.grep myArray, (e) -> e.id == foo_id
myArray.pop foo

Here's how I'd go about it in pure JavaScript, in the most minimal manner I can think of that works in ECMAScript 3 or later. It returns as soon as a match is found.

var getKeyValueById = function(array, key, id) {
    var testArray = array.slice(), test;
    while(test = testArray.pop()) {
        if (test.id === id) 
            return test[key]
    }
    // return undefined if no matching id is found in array
    return;
}

var myArray = [{'id':'73', 'foo':'bar'}, {'id':'45', 'foo':'bar'}]
var result = getKeyValueById(myArray, 'foo', '45');

// result is 'bar', obtained from object with id of '45'

I really liked the answer provided by Aaron Digulla but needed to keep my array of objects so I could iterate through it later. So I modified it to

	var indexer = {};
	for (var i = 0; i < array.length; i++) {
	    indexer[array[i].id] = parseInt(i);
	}
	
	//Then you can access object properties in your array using 
	array[indexer[id]].property

Iterate over any item in the array. For every item you visit, check that item's id. If it's a match, return it.

If you just want teh codez:

function getId(array, id) {
    for (var i = 0, len = array.length; i < len; i++) {
        if (array[i].id === id) {
            return array[i];
        }
    }
    return null; // Nothing found
}

And the same thing using ECMAScript 5's Array methods:

function getId(array, id) {
    var obj = array.filter(function (val) {
        return val.id === id;
    });

    // Filter returns an array, and we just want the matching item.
    return obj[0];
}

As long as the browser supports ECMA-262, 5th edition (December 2009), this should work, almost one-liner:

var bFound = myArray.some(function (obj) {
    return obj.id === 45;
});

Starting from aggaton's answer, this is a function that actually returns the wanted element (or null if not found), given the array and a callback function that returns a truthy value for the "correct" element:

function findElement(array, callback) {
    var elem;
    return array.some(function(e) {
        if (callback(e)) {
            elem = e;
            return true;
        }
    }) ? elem : null;
});

Just remember that this doesn't natively work on IE8-, as it doesn't support some. A polyfill can be provided, alternatively there's always the classic for loop:

function findElement(array, callback) {
    for (var i = 0; i < array.length; i++)
        if (callback(array[i])) return array[i];
    return null;
});

It's actually faster and more compact. But if you don't want to reinvent the wheel, I suggest using an utility library like underscore or lodash.

Use:

var retObj ={};
$.each(ArrayOfObjects, function (index, obj) {

        if (obj.id === '5') { // id.toString() if it is int

            retObj = obj;
            return false;
        }
    });
return retObj;

It should return an object by id.

This solution may helpful as well:

Array.prototype.grep = function (key, value) {
    var that = this, ret = [];
    this.forEach(function (elem, index) {
        if (elem[key] === value) {
            ret.push(that[index]);
        }
    });
    return ret.length < 2 ? ret[0] : ret;
};
var bar = myArray.grep("id","45");

I made it just like $.grep and if one object is find out, function will return the object, rather than an array.

Shortest,

var theAnswerObj = _.findWhere(array, {id : 42});

Consider "axesOptions" to be array of objects with an object format being {:field_type => 2, :fields => [1,3,4]}

function getFieldOptions(axesOptions,choice){
  var fields=[]
  axesOptions.each(function(item){
    if(item.field_type == choice)
        fields= hashToArray(item.fields)
  });
  return fields;
}