Benchmark: array includes vs object key lookup

Script Preparation code:

var a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
var b = { 1: {}, 2: {}, 3: {}, 4: {}, 5: {}, 6: {}, 7: {}, 8: {}, 9: {}, 10: {} };

Tests:

includes
return a.includes(9)
lookup
return b[9]

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

lookup

19.1M/s

includes

16.3M/s

Fastest: lookup (1.2x faster)

View exact numbers

✓ lookup: 19,114,390 ops/sec
• includes: 16,288,790 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
lookup

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/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Mac OS X 10.15.7

View result in a separate tab

lookup

154.5M/s

includes

85.5M/s

View exact numbers

Test name	Executions per second
✓ lookup	154,475,792 Ops/sec
includes	85,495,864 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the provided benchmark!

**Benchmark Overview**

The MeasureThat.net website is used to create and run JavaScript microbenchmarks, which allows users to compare the performance of different approaches on various devices.

**Script Preparation Code**

The script preparation code defines two variables:

* `a`: an array with 10 elements (from 1 to 10)
* `b`: an object with 10 properties, where each property has an empty object as its value. The keys of the object match the values in the `a` array.

**Benchmark Definition**

The benchmark definition consists of two test cases:

1. **includes**: This test case uses the `includes()` method on the `a` array to check if 9 is included.
2. **lookup**: This test case uses direct indexing on the object `b` to access its value at key 9.

**Comparison Options**

The benchmark compares two approaches:

* Using the `includes()` method on an array
* Directly accessing an object by key

**Pros and Cons of each approach:**

* **includes() method:**
	+ Pros:
		- More readable and maintainable code (less magic numbers)
		- Easier to understand what's happening under the hood
	+ Cons:
		- Potential performance overhead due to the method call
		- May not be optimized by the browser
* **Direct indexing:**
	+ Pros:
		- More direct and efficient access to object properties
		- Can potentially be optimized by the browser
	+ Cons:
		- Less readable and maintainable code (more magic numbers)
		- May require more complex logic for handling errors or edge cases

**Library Used:**

None, as this is a basic benchmark without any external libraries.

**Special JS Features/Syntax:**

* **includes() method**: Introduced in ECMAScript 2015 (ES6), the `includes()` method provides a convenient way to check if an array includes a specific value.
* **Direct indexing**: This syntax is a common pattern in JavaScript, but it's not specific to any particular feature or syntax.

**Other Alternatives:**

If you wanted to modify this benchmark to explore other approaches, here are some ideas:

1. Use `indexOf()` instead of `includes()`.
2. Add more elements to the array and object.
3. Use a different data structure, such as a Set or Map.
4. Implement a custom indexing mechanism for the object.
5. Compare the performance with alternative JavaScript implementations (e.g., Node.js, WebAssembly).

I hope this explanation helps you understand the benchmark!

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

Comparing performance of: `includes vs lookup`

Created: 5 years ago by: Guest

Go to the latest result

includes

lookup

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 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 lookup (version: 0) Benchmark.js

Comparing performance of: includes vs lookup

Created: 5 years ago by: Guest

Go to the latest result

includes

lookup

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 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 lookup`