Benchmark: set.has vs. Object key lookup

Script Preparation code:

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

Tests:

includes
return a.includes(9)
key lookup
return !!b['9']

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

includes

28.2M/s

key lookup

28.1M/s

View exact numbers

✓ includes: 28,218,228 ops/sec
• key lookup: 28,133,730 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
key 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/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Mac OS X 10.15.7

View result in a separate tab

key lookup

145.5M/s

includes

82.6M/s

View exact numbers

Test name	Executions per second
✓ key lookup	145,475,824 Ops/sec
includes	82,571,984 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Overview**

The provided benchmark compares two approaches to check if a value exists in an array: using the `includes()` method and direct key lookup on an object. The benchmark is designed to measure the performance difference between these two methods.

**Options Compared**

There are two options being compared:

1. **`includes()` Method**: This method checks if a specified value exists in an array by iterating through the elements of the array.
2. **Direct Key Lookup (Object)**: This approach directly accesses an object's property using its key, which is equivalent to checking if a key exists in an object.

**Pros and Cons**

**`includes()` Method**

Pros:

* More intuitive and readable code
* Works with arrays of any type, not just primitive values
* Can be used to check for membership in other data structures like sets or maps

Cons:

* May perform unnecessary work if the array is large and the value is not present
* Can be slower than direct key lookup for small arrays or specific use cases

**Direct Key Lookup (Object)**

Pros:

* Generally faster than the `includes()` method, especially for small arrays or objects
* Can be optimized for specific use cases, like checking for existence in a large object

Cons:

* Requires knowledge of object properties and their behavior
* May not be as readable or maintainable for complex data structures

**Library/Functionality Used**

In this benchmark, the `includes()` method is a built-in JavaScript function. Direct key lookup on an object is achieved using the syntax `obj[key]`, where `key` is the property name being accessed.

**Special JS Feature/Syntax**

None are explicitly mentioned in the provided benchmark definition or test cases. However, it's worth noting that this benchmark assumes a modern JavaScript engine and does not account for older engines or specific features like ES6+ syntax.

**Other Alternatives**

If you're interested in exploring alternative approaches to checking for membership in an array or object, here are a few options:

* Using `Array.prototype.some()` method: This method checks if at least one element in the array meets a condition.
* Using `Object.values()` and `Array.prototype.includes()`: This approach iterates through the values of an object and then uses `includes()` to check for presence.

Keep in mind that these alternatives may have different performance characteristics or trade-offs compared to the original `includes()` method and direct key lookup approaches.

set.has vs. Object key lookup (version: 0) Benchmark.js

Comparing performance of: `includes vs key lookup`

Created: 5 years ago by: Registered User

Go to the latest result

includes

key lookup

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

set.has vs. Object key lookup (version: 0) Benchmark.js

Comparing performance of: includes vs key lookup

Created: 5 years ago by: Registered User

Go to the latest result

includes

key lookup

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 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 key lookup`