Benchmark: Array vs object - MeasureThat.net

Script Preparation code:

var n = 80;
var a = [];
var obj = {};
for (var i=0; i<a.length; i++) {
  a[i] = i;
  obj["obj" + i] = i;
}

Tests:

Array
r = Math.floor(Math.random()*n); for (var i=0; i<a.length; i++) { if (a[i] == r) break; }
Object
r = Math.floor(Math.random()*n); var i = obj["obj"+r];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array
Object

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
Array	6011894.5 Ops/sec
Object	3685167.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested, compared, and the pros and cons of different approaches.

**Benchmark Overview**

The benchmark compares two approaches:

1. **Array**: An array is used to store numbers from 0 to `n-1`.
2. **Object**: An object (specifically, a plain JavaScript object) is created with properties named "objX" for each number `i` from 0 to `n-1`.

**Test Cases**

There are two test cases:

1. **Array Test Case**:
```javascript
for (var i=0; i<a.length; i++) {
    if (a[i] == r) break;
}
```
This test case iterates over the array `a` and checks if the current element `a[i]` is equal to a randomly generated number `r`. The loop breaks as soon as a match is found.

2. **Object Test Case**:
```javascript
var i = obj["obj" + r];
```
This test case uses the object's property access to retrieve the value associated with the key `"obj" + r`.

**Pros and Cons**

1. **Array Approach**:
	* Pros: Arrays are optimized for fast iteration, and this approach can take advantage of browser optimizations like array caching.
	* Cons: This approach requires iterating over the entire array, which can be slower than accessing a single property on an object.
2. **Object Approach**:
	* Pros: Accessing properties on an object is typically faster than iterating over an array, especially if the property access is cached.
	* Cons: This approach relies on the browser's ability to cache property accesses, and it may not be as efficient as iterating over an array.

**Library Usage**

None of the test cases use a specific library. However, plain JavaScript objects are used, which implies that the benchmark is testing the built-in JavaScript features for accessing properties.

**Special JS Features or Syntax**

There is no special JS feature or syntax being tested in this benchmark. The code is straightforward and uses standard JavaScript features.

**Other Alternatives**

To compare these two approaches, you could also consider using other data structures like sets or hash tables. Additionally, you might want to test different iteration techniques, such as iterating over an array with a `for...of` loop or using the `Array.prototype.forEach()` method.

If you're interested in exploring alternative implementations, here are some additional ideas:

* Use a set or hash table data structure instead of arrays.
* Iterate over the object properties using a `for...in` loop.
* Use a library like Lodash or Ramda to access property values on an object.
* Test different caching strategies for accessing array elements or object properties.

Keep in mind that these alternatives might introduce additional complexity and may not be as efficient as the original implementations.

Related benchmarks:

Array vs object (version: 0)

Comparing performance of: Array vs Object

Created: 8 years ago by: Guest

Jump to the latest result

Array

Object

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):