Benchmark: set.has vs. Object key

Script Preparation code:

var a = new Set([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:

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
has
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/605.1.15 (KHTML, like Gecko) Version/17.3.1 Safari/605.1.15

Browser/OS: Safari 17 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
has	484575872.0 Ops/sec
key lookup	473972352.0 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 provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches: `Set.has()` and object key lookup (`!!b['9']`). The test case uses JavaScript, which provides several features that allow for concise and expressive code.

**Options Compared**

There are two options compared:

1. **`Set.has()`**: This method checks if a specific value exists in a Set data structure.
2. **Object key lookup**: This approach uses the `!!b['9']` syntax to check if a property (in this case, the string `'9'`) exists as a key in an object (`b`).

**Pros and Cons of Each Approach**

1. **`Set.has()`**:
	* Pros:
		+ Faster lookup times since Sets are optimized for efficient membership testing.
		+ More concise code compared to traditional object key lookup.
	* Cons:
		+ May require additional memory allocation if the Set grows dynamically.
		+ Not all browsers support Sets (although most modern ones do).
2. **Object Key Lookup (`!!b['9']`)**:
	* Pros:
		+ More familiar and widely supported syntax across different browsers and platforms.
		+ No additional memory allocation required.
	* Cons:
		+ Slower lookup times compared to `Set.has()`, especially for large datasets.

**Library/Feature**

The benchmark uses the JavaScript `Set` object, which provides an efficient way to store unique values. The `has()` method is a part of this API.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax used in this benchmark that would require additional explanation. However, it's worth noting that the use of the nullish coalescing operator (`??`) is not present in this example, but it's sometimes used to simplify object key lookups by providing a default value if the property doesn't exist.

**Other Alternatives**

If you wanted to explore alternative approaches for this benchmark, here are a few options:

1. **Array.includes()**: This method checks if a specific value exists within an array.
2. **Object.prototype.hasOwnProperty()**: This method checks if a property exists as a direct property of an object (not inherited from prototype chains).
3. **Array.indexOf() / Array.lastIndexOf()**: These methods search for the first or last occurrence of a specified value in an array.

Keep in mind that each alternative approach has its own trade-offs, such as performance characteristics and code readability.

For this specific benchmark, using `Set.has()` provides a clear performance advantage over object key lookup (`!!b['9']`) on modern browsers.

Related benchmarks:

set.has vs. Object key (version: 0)

Comparing performance of: has vs key lookup

Created: 2 years ago by: Guest

Jump to the latest result

has

key lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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