Finding value of javascript object in an array

Question

Hi really new to javascript and am hoping to get some help with a problem im facing.

So I basically have an array that stores objects. Each object contains an id and a variable i which is a number. My question is this: how can I extract the value of i from the object array with the id value? The id that I am using would already have been stored in the array with an i value.

var i = 1;
var id;
var b = {}; 
var y = [];

if(condition) {

  b = {"123":i};

  y.push(b);

}

if(condition) {
  id = 123;
  //Find corresponding i value for id "123" from object array y
  i = ?;
}

Possible duplicate of Find object by id in an array of JavaScript objects — Jared Smith
– Jared Smith, Commented Jun 28, 2017 at 16:41
The suggested solutions are for jQuery. Will they work for javascript too? @JaredSmith — user3702643
– user3702643, Commented Jun 28, 2017 at 16:45
Array#find is not jQuery. I actually don't see any jQuery solutions suggested (yet). And remember, jQuery is JavaScript. — Mark Rabey
– Mark Rabey, Commented Jun 28, 2017 at 17:17

Xotic750 · Accepted Answer · 2017-06-28 18:06:42Z

1

An example with Array#find

var hasOwn = Function.prototype.call.bind(Object.prototype.hasOwnProperty);
var i = 1;
var id;
var b = {};
var y = [];

var condition = true;
if (condition) {
  b = {
    "123": i
  };

  y.push(b);
}

if (condition) {
  id = 123;
  // Find corresponding i value for id "123" from object array y
  // i = ? ;
  var found = y.find(function(o) {
    return hasOwn(o, id);
  });
  var f = found ? found[id] : found;
  console.log(f);
}

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/es5-shim/4.5.9/es5-shim.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/es5-shim/4.5.9/es5-sham.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/json3/3.3.2/json3.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/es6-shim/0.35.3/es6-shim.js"></script>
<script type="text/javascript" src="https://wzrd.in/standalone/es7-shim@latest"></script>

edited Jun 28, 2017 at 18:06

answered Jun 28, 2017 at 17:00

Xotic750

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4 Comments

abbotto Over a year ago

While this answer does find the value of "i", the items array doesn't match the example that was given by the OP.

Xotic750 Over a year ago

No, because this was posted before the Q was edited. :)

abbotto Over a year ago

There can be issues with calling "hasOwnProperty" in some browsers. Example: stackoverflow.com/questions/8157700/…

Xotic750 Over a year ago

Like I care about IE8. :D

Rahul Singh · Accepted Answer · 2017-06-28 16:44:30Z

0

Just use ObjectName[Key] this is enoughto get you the value Like b[123]

answered Jun 28, 2017 at 16:44

Rahul Singh

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Comments

Ved · Accepted Answer · 2017-06-28 17:02:32Z

0

Many ways to do this. Here is one of them.

var arr = [{id:1},{id:123}];

var obj = arr.filter(function(val){
   if(val.id===123)
  return val

})

console.log(obj,'obj')

edited Jun 28, 2017 at 17:02

answered Jun 28, 2017 at 16:45

Ved

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7 Comments

user3702643 Over a year ago

the output i get for this is [] 'obj'. Any idea why?

Ved Over a year ago

@user3702643 have you run the snippet.

user3702643 Over a year ago

I ran it on my local environment. Cant seem to get the same result.

Xotic750 Over a year ago

Array#filter will always give you an array, and it may contain 0 or 1 or more elements. It's probably not the best choice in this use case.

Ved Over a year ago

@Xotic750 correct. but we dont know if the ID is duplicate.

|

elqueso101 · Accepted Answer · 2017-06-28 17:29:17Z

0

const stuff = [
  {
    name: 'Leonardo',
    id: 100
  },
  {
    name: 'Donatello',
    id: 101
  },
  {
    name: 'Raphael',
    id: 102
  },
  {
    name: 'Michaelangelo',
    id: 103
  },
];

First, use the Array.prototype.find() method on the array to find the object within it that has the desired ID and store it in the entry variable. Then, log the value corresponding to the name key within that object.

const desired = 102;
const entry = stuff.find(item => item.id === desired);

console.log(entry.name);

answered Jun 28, 2017 at 17:29

elqueso101

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Comments

abbotto · Accepted Answer · 2017-06-28 18:34:44Z

0

You can loop through the array and get the object property value as follows:

var arr = [
    {"123": "valueA"},
    {"456": "valueB"}
];

const id = "123";
let value;

arr.some(obj => {
    if (obj[id] || obj[id] === 0) value = obj[id];
});

console.log(value);

Documentation for "Array.some" method

edited Jun 28, 2017 at 18:34

answered Jun 28, 2017 at 16:55

abbotto

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4 Comments

Xotic750 Over a year ago

It would be better to use Array#some than Array#forEach

Xotic750 Over a year ago

What if the value for i was 0?

abbotto Over a year ago

The correct value for "0" should be returned - now that I've updated the answer. :)

Xotic750 Over a year ago

The keywords const and let, and Arrow functions can cause an issue in some browsers. ;)

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