Benchmark: array includes vs object key

Script Preparation code:

var obj = (new Array(1000)).fill(null).reduce((prev, newVal) => {prev[Math.random() + ''] = Math.random() + ''; return prev; }, { sausage: 'tst' });
var array = Object.keys(obj);

Tests:

Includes
array.includes('sausage')
Object[key]
obj['sausage']

Historical Performance Data aggregated from 44 community runs

Desktop Results:

Chrome 38 runs

Includes

24.2M/s

Object[key]

22.8M/s

View exact numbers

✓ Includes: 24,247,956 ops/sec
• Object[key]: 22,775,244 ops/sec

Firefox 6 runs

Object[key]

1020.2M/s

Includes

51.4M/s

Fastest: Object[key] (19.9x faster)

View exact numbers

✓ Object[key]: 1,020,164,480 ops/sec
• Includes: 51,368,352 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Includes
Object[key]

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36

Browser/OS: Chrome 139 on Mac OS X 10.15.7

View result in a separate tab

Includes

201.4M/s

Object[key]

156.4M/s

View exact numbers

Test name	Executions per second
✓ Includes	201,350,080 Ops/sec
Object[key]	156,360,016 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 provided benchmark and its test cases.

**Benchmark Overview**

MeasureThat.net is testing the performance of two different approaches to check if an array contains a specific value: `array.includes()` and accessing an object using its key (`obj['sausage']`).

**Script Preparation Code**

The script preparation code generates a large array with 1000 random keys, where each key has a unique string value. The key is stored in the `obj` variable.

```javascript
var obj = (new Array(1000)).fill(null).reduce((prev, newVal) => {
    prev[Math.random() + ''] = Math.random() + '';
    return prev;
}, { sausage: 'tst' });
```

This code creates a large array and populates it with random keys using the `reduce()` method. The key is stored in an object (not explicitly shown in the provided code).

**Html Preparation Code**

The HTML preparation code is empty, which means that no additional setup or rendering is required for this benchmark.

**Test Cases**

There are two test cases:

1. **Includes**
```javascript
"array.includes('sausage')"
```
This test case uses the `includes()` method to check if the array contains the string `'sausage'`.

2. **Object[key]**
```javascript
"obj['sausage']"
```
This test case accesses the value associated with the key `'sausage'` in the `obj` object.

**Library and Purpose**

The `reduce()` method is a built-in JavaScript method used to apply a function to each element of an array and reduce it to a single output. In this benchmark, it's used to generate the random keys for the array.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes being tested in this benchmark. It only uses standard JavaScript methods and data structures.

**Pros and Cons of Approaches**

1. **array.includes()**
	* Pros:
		+ Simple and concise
		+ Fast (it's a built-in method)
	* Cons:
		+ May not be optimized for large arrays, potentially leading to slower performance
2. **Object[key]**
	* Pros:
		+ Direct access to the value associated with a key
	* Cons:
		+ May be slower due to the need to look up the key in the object

**Other Alternatives**

1. `array.indexOf()` or `array.lastIndexOf()`: These methods can also be used to check if an array contains a specific value, but they may have different performance characteristics depending on the browser and JavaScript engine.
2. `Array.prototype.some()` or `Array.prototype.every()`: These methods can be used with callback functions to iterate over the array and check for the presence of a value.

In summary, this benchmark is testing the performance of two simple yet distinct approaches to check if an array contains a specific value. The results will provide insight into how these different methods perform in various browsers and JavaScript engines.

array includes vs object key (version: 0) Benchmark.js

performance comparison of ways to find if an array contains a value

Comparing performance of: `Includes vs Object[key]`

Created: 6 years ago by: Guest

Go to the latest result

Includes

Object[key]

Historical Performance Data aggregated from 44 community runs

Desktop Results:

Chrome 38 runs

Firefox 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

array includes vs object key (version: 0) Benchmark.js

performance comparison of ways to find if an array contains a value

Comparing performance of: Includes vs Object[key]

Created: 6 years ago by: Guest

Go to the latest result

Includes

Object[key]

Historical Performance Data aggregated from 44 community runs

Desktop Results:

Chrome 38 runs

Firefox 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `Includes vs Object[key]`