Benchmark: set.has vs. object in 2

Script Preparation code:

var a = {1 : true, 4: true, 6: true, 9: true, 14: true};
var b = new Set(Object.keys(a));

Tests:

in object
let r = false; for (let i = 0; i < 100; ++i) { r = !!a[i]; }
lookup
let r = false; for (let i = 0; i < 100; ++i) { r = b.has(i) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
in object
lookup

Fastest: N/A

Slowest: N/A

Latest run results:

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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 definition and test cases to understand what's being tested.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmarking test case for two different approaches: `set.has` vs. checking if an object has a certain key using the `in` operator.

**Script Preparation Code**

The script preparation code creates two variables:

* `a`: an object with keys 1, 4, 6, 9, and 14 set to `true`.
* `b`: a new Set created from the keys of `a`.

**Html Preparation Code**

There is no HTML preparation code provided.

**Test Cases**

The benchmark definition includes two test cases:

1. **"in object"`**: This test case iterates over an array (not shown in the JSON) and checks if each element is present in the `a` object using the `in` operator.
2. **"lookup"`**: This test case iterates over the same array as above, but checks if each element is present in the Set `b` using the `has` method.

**Comparison of Approaches**

The two approaches being tested are:

* Using the `in` operator to check if an object has a certain key ( Approach A).
* Using the `has` method on a Set to check if it contains a specific value (Approach B).

Pros and Cons:

* **Approach A (in operator)**:
	+ Pros: generally faster than using sets, as it's a simple property lookup.
	+ Cons: may not be as efficient for large datasets, as it requires iterating over the object's keys.
* **Approach B (has method on Set)**:
	+ Pros: efficient for checking if an element is present in a set, especially for large datasets.
	+ Cons: slower than using the `in` operator, as it requires traversing the set's internal data structure.

**Library and Special JS Feature**

The benchmark uses the `Set` object, which is a built-in JavaScript library. The `has` method on Set is used to check if an element is present in the set.

There are no special JavaScript features or syntaxes being tested in this benchmark.

**Alternatives**

Other alternatives for checking if an element is present in an object or a set include:

* Using the `Object.keys()` and `includes()` methods.
* Using a library like Lodash's `isEqual()` function, which can perform deep equality checks.
* Using a custom implementation that iterates over the object or set's internal data structure.

Keep in mind that these alternatives may have different performance characteristics compared to using the built-in `in` operator and `has` method on Set.

Related benchmarks:

set.has vs. object in 2 (version: 0)

Comparing performance of: in object vs lookup

Created: 3 years ago by: Guest

Jump to the latest result

in object

lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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