In an array of objects, fastest way to find the index of an object whose attributes match a search

Question

Maybe you would like to use higher-order functions such as "map". Assuming you want search by 'field' attribute:

var elementPos = array.map(function(x) {return x.id; }).indexOf(idYourAreLookingFor);
var objectFound = array[elementPos];

The simplest and easiest way to find element index in array.

ES5 syntax: [{id:1},{id:2},{id:3},{id:4}].findIndex(function(obj){return obj.id == 3})

ES6 syntax: [{id:1},{id:2},{id:3},{id:4}].findIndex(obj => obj.id == 3)

The new Array method .filter() would work well for this:

var filteredArray = array.filter(function (element) { 
    return element.id === 0;
});

jQuery can also do this with .grep()

edit: it is worth mentioning that both of these functions just iterate under the hood, there won't be a noticeable performance difference between them and rolling your own filter function, but why re-invent the wheel.

If you care about performance, dont go with find or filter or map or any of the above discussed methods

Here is an example demonstrating the fastest method. HERE is the link to the actual test

Setup block

var items = []

for(var i = 0; i < 1000; i++) {
    items.push({id: i + 1})
}

var find = 523

Fastest Method

var index = -1
for(var i = 0; i < items.length; i++) {
    if(items[i].id === find) {
        index = i;
        break;
    }
}

Slower Methods

items.findIndex(item => item.id === find)

SLOWEST method

items.map(item => item.id).indexOf(find);

array.forEach(function (elem, i) {  // iterate over all elements of array
    indexes[elem.id] = i;           // take the found id as index for the
});                                 // indexes array and assign i

the result is a look up list for the id. with the given id we get the index of the record.

Since there's no answer using regular array find:

var one = {id: 1, name: 'one'};
var two = {id: 2, name:'two'}
var arr = [one, two] 

var found = arr.find((a) => a.id === 2)

found === two // true

arr.indexOf(found) // 1