Benchmark: set.has vs. array.includes vs in operator (with strings)

Script Preparation code:

var a = [];
for (let i = 0; i < 100_000; i++) {
  a.push(i.toString());
}
var b = new Set(a)
var c = {}
for (const key of a) {
  c[key] = 0; 
}

Tests:

includes
return a.includes("9")
lookup
return b.has("9")
in
return "9" in c

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
includes
lookup
in

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what's being tested.

**Benchmark Description**

The benchmark measures the performance of three different approaches for checking if an element exists in a collection:

1. `array.includes()`: A method to check if a specified value exists in an array.
2. `set.has()`: A method to check if a value exists in a Set data structure.
3. The "in" operator: A keyword that checks if a value exists as a property of an object.

**Script Preparation Code**

The script preparation code creates three arrays:

* `a`: An array with 100,000 elements, each being the string representation of a number from 0 to 99,999.
* `b`: A Set created by pushing all elements of `a` into it.
* `c`: An empty object that will be used as a test subject for the "in" operator.

The script then creates an array `d` with the same elements as `a`, but in reverse order. This is not directly relevant to the benchmark, but might affect the results if it's not accounted for.

**Html Preparation Code**

There is no HTML preparation code provided.

**Individual Test Cases**

Each test case measures the performance of one of the three approaches:

1. `includes`: Measures the performance of `array.includes()`.
2. `lookup`: Measures the performance of `set.has()`.
3. `in`: Measures the performance of the "in" operator on object `c`.

**Library and Purpose**

* No libraries are explicitly mentioned in the provided code.
* However, it's worth noting that the `Set` data structure is a built-in JavaScript API for working with collections.

**Special JS Feature or Syntax**

The benchmark uses arrays and objects as test subjects. The "in" operator checks if an element exists as a property of an object, which is a language feature in JavaScript.

**Pros and Cons of Different Approaches**

Here's a brief overview of the pros and cons of each approach:

1. `array.includes()`:
	* Pros: Fast, widely supported, and easy to use.
	* Cons: May perform poorly for very large arrays due to its reliance on searching through the array from start to end.
2. `set.has()`:
	* Pros: Very fast for checking existence in a set, especially when dealing with unique values.
	* Cons: May have higher overhead for inserting and deleting elements, which can impact overall performance.
3. "in" operator:
	* Pros: Fast and efficient for checking presence as an object property.
	* Cons: May be slower than the other two approaches for very large objects or arrays.

**Other Alternatives**

If you were to use a different approach or library for this benchmark, some alternatives could include:

* Using `Map` instead of an object (`c`) for the "in" operator test case.
* Utilizing libraries like Lodash or Ramda for additional functionality or performance enhancements.
* Experimenting with other data structures like linked lists or trees.

Keep in mind that these alternatives would require significant changes to the benchmark code and might not provide a fair comparison.

Latest run results:

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

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_1_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.1.1 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 17 on iOS 17.1.1

View result in a separate tab

Test name	Executions per second
includes	4991000.0 Ops/sec
lookup	14949317.0 Ops/sec
in	9690930.0 Ops/sec

Related benchmarks:

set.has vs. array.includes vs in operator (with strings) (version: 0)

Comparing performance of: includes vs lookup vs in

Created: one year ago by: Guest

Jump to the latest result

includes

lookup

in

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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