Arrays vs. Objects in JavaScript: Which is Faster for Retrieving a Single Object with a Long Numerical ID?

Array vs. Object Efficiency in JavaScript: Retrieving a Single Object with a Long Numerical ID

Problem Statement:

When efficiently storing a large number of objects and needing to retrieve them by a unique, long numerical ID, it's crucial to determine the best data structure: an array or an object.

Array Option:

<code class="javascript">var a = [{id: 29938, name: 'name1'},
         {id: 32994, name: 'name1'}];</code>

To locate an object in an array, a linear search is required:

<code class="javascript">function getObject(id) {
    for (var i=0; i < a.length; i++) {
        if (a[i].id == id)
            return a[i];
    }
}</code>

Object Option:

<code class="javascript">var a = {};
a[29938] = {id: 29938, name: 'name1'};
a[32994] = {id: 32994, name: 'name1'};</code>

With an object, retrieval is direct based on the ID used as the key:

<code class="javascript">function getObject(id) {
    return a[id];
}</code>

Analysis:

In general, arrays are slightly faster than objects for retrieving individual elements, particularly with large arrays. This is because objects have key-value pairs, which require additional lookup overhead compared to the simple indexing of arrays.

Performance Test Results (2017):

A performance test conducted in 2017 revealed that an array is notably faster than both a holey array and an object for retrieving a single object.

Sorting:

The sorting performance depends on the sorting algorithm used and the number of elements. While arrays can be sorted more efficiently than objects using built-in methods like Array.sort(), the difference may not be significant for smaller datasets.

Conclusion:

If the primary operation is retrieving a single object based on its ID, an array is generally more efficient than an object, especially for large numbers of objects. However, if sorting is a frequent requirement, the choice of data structure may require further testing and considerations.

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