Getting index of array object element given multiple object keys

Question

I know given a single key (for example, if I know the object.name = 'Sam') using:

var index = array.map(function(el) {return el.name}).indexOf('Sam');

I can get the index of the array element with object.name = 'Sam' However say I have several elements with object.name ='Sam' in the array, but now I know know the object.name, object.age and object.size - is it possible to adapt the above code to get the index but also checking against object.age and object.size?

Since you have several elements with same name, whose index you're trying to find out..?! — T J, Oct 18 '14 at 17:48
@TJ The one which not only the name matches, but also the age matches and size matched. (This one will be unique, so I have no worry about duplicates) — AlwaysNeedingHelp, Oct 18 '14 at 17:50
you should probably use filter instead of getting the index. with filter, you just filter for each property, one after the next (it's associative). — dandavis, Oct 18 '14 at 18:58

T J · Accepted Answer · 2014-10-18T18:28:03.020

Assuming you have the values in variables such as name, age and size as you mentioned in comments, You can use a function like:

function findInArray(arr) {
  for (var i = 0; i < arr.length; i++) {
    var el = arr[i];
    if (el.name == name && el.age == age && el.size == size)
        return i;
  }
 return -1;
};

Which will return the index of object in array if match is found, and -1 otherwise...

var data = [{
    name: "Sis",
    age: "17",
    size: "10"
  }, {
    name: "Sam",
    age: "17",
    size: "10"
  }, {
    name: "Som",
    age: "17",
    size: "10"
  }],
  name = "Sam",
  age = "17",
  size = "10";

function findInArray(arr) {
  for (var i = 0; i < arr.length; i++) {
    var el = arr[i];
    if (el.name == name && el.age == age && el.size == size)
      return i;
  }
  return -1;
};
console.log(findInArray(data));

score 0 · Answer 2 · edited May 23 '17 at 12:15

If you're using the awesome underscore library there's a _.findWhere function.

var sam21 = _.findWhere(people, {
  name: 'Sam', 
  age: 21
});

if you want something without a whole other library you can use .filter.

var sam21 = people.filter(function(person) {
  return person.age === 21 && person.name === 'Sam';
});

I just noticed you're looking for the index. This answer can be useful: https://stackoverflow.com/a/12356923/191226

score 0 · Answer 3 · answered Sep 28 '16 at 10:46

You could use a function like this one

indexOfObjectArray = function(array, keyvalues) {
for (var i = 0; i < array.length; i++) {
    var trueCount = 0;
    for (var j = 0; j < keyvalues.length; j++) {
        if (array[i][keyvalues[j]['key']] == keyvalues[j]['value']) {
            trueCount++;
        }
    }
    if (trueCount === keyvalues.length) return i;
}
return -1; }

and use it like that for example:

var yourArray = [{id: 10, group: 20},...];
var keyvalues = [
{ 'key': 'id', 'value': 10 },
{ 'key': 'group', 'value': 20 }]; 

var index = indexOfObjectArray(yourArray, keyvalues );

This function will return the index of an object that has id = 10 and group = 20

Getting index of array object element given multiple object keys

3 Answers3