Benchmark: Lazy set - MeasureThat.net

Script Preparation code:

var obj = { b: false, c: false }

Tests:

In
if (!('a' in obj)) { obj.a = new Set(); } obj.a.add(42);
!
if (!obj.a) { obj.a = new Set(); } obj.a.add(42);
!== undefined
if (obj.a === undefined) { obj.a = new Set(); } obj.a.add(42);
??=
(obj.a ??= new Set()).add(42);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
In
!
!== undefined
??=

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 dive into the explanation of the benchmark.

**Benchmark Purpose**

The benchmark measures the performance of different approaches to lazy set initialization in JavaScript, specifically when using the `Set` data structure. The test cases aim to determine which approach is most efficient in terms of execution speed.

**Options Compared**

There are four options compared:

1. **No conditional statement**: This approach initializes the `obj.a` property only if it's `undefined`.
2. **Using `in` operator**: This approach checks if `obj.a` is an own property of the object using the `in` operator and initializes it to a new `Set` if not.
3. **Using triple equals (`===`)**: This approach checks if `obj.a` has a value and only initializes it to a new `Set` if it's `undefined`.
4. **Using nullish coalescing operator (`??=`)**: This approach initializes the `obj.a` property to a new `Set` using the nullish coalescing operator.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **No conditional statement**
	* Pros:
		+ Simple and concise code
	* Cons:
		+ May not be optimal for all use cases, as it assumes `obj.a` will never be initialized before
2. **Using `in` operator**
	* Pros:
		+ More expressive and readable code
	* Cons:
		+ May introduce performance overhead due to the `in` operator check
3. **Using triple equals (`===`)**
	* Pros:
		+ Clear and concise code
	* Cons:
		+ May not be as efficient as other approaches, as it requires a value check
4. **Using nullish coalescing operator (`??=`)**
	* Pros:
		+ Concise and expressive code
	* Cons:
		+ Less well-known than other operators, which may lead to confusion for some developers

**Library and Special JS Features**

The benchmark uses the `Set` data structure, which is a built-in JavaScript library. No special JavaScript features or syntax are used in this benchmark.

**Other Alternatives**

If you were to implement lazy set initialization using different approaches, here are a few alternatives:

1. **Using an object property**: You could initialize the `obj.a` property directly if it's not already set.
2. **Using a function**: You could define a function that returns the new `Set` instance when called for the first time.
3. **Using a closure**: You could use a closure to capture the initialization logic and reuse it across multiple calls.

However, these alternatives may have different performance characteristics and trade-offs compared to the options tested in this benchmark.

Related benchmarks:

Lazy set (version: 0)

Comparing performance of: In vs ! vs !== undefined vs ??=

Created: 3 years ago by: Guest

Jump to the latest result

In

!

!== undefined

??=

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):