Benchmark: In operator vs Object Accessors

Tests:

in
const a = { b: "c" } if ("b" in a) { console.log(a.b) }
Object accessor
const a = { b: "c" } if (a.b) { console.log(a.b) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
in
Object accessor

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Windows

View result in a separate tab

Test name	Executions per second
in	210458.2 Ops/sec
Object accessor	353293.2 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 JSON data and explain what's being tested.

**Benchmark Definition**

The benchmark definition is a simple JavaScript snippet that tests two different approaches to accessing property values in an object:

1. **`in` operator**: This approach uses the `in` keyword to check if a key exists in an object.
2. **Object Accessors**: This approach uses dot notation (`a.b`) or bracket notation (`a['b']`) to access property values directly.

**Options being compared**

The benchmark is comparing two options:

1. Using the `in` operator
2. Using object accessors (dot notation and bracket notation)

**Pros and Cons of each approach**

* **`in` operator**:
	+ Pros:
		- Fast and efficient, as it only requires a single lookup operation.
		- Portable across different browsers and environments.
	- Cons:
		- May not work as expected in certain edge cases (e.g., when the object has multiple properties with the same key).
		- Can be slower than other approaches due to the additional overhead of the lookup operation.
* **Object Accessors**:
	+ Pros:
		- Typically faster and more efficient than the `in` operator, as it involves a single property access operation.
		- More readable and intuitive for many developers.
	+ Cons:
		- May not work in older browsers or environments that don't support dot notation and bracket notation.

**Library usage**

Neither of the benchmarked code snippets uses any external libraries. The `in` operator is a built-in JavaScript keyword, while object accessors are part of the language itself.

**Special JS feature or syntax**

There is no special JavaScript feature or syntax being used in these benchmarks. Both approaches rely on standard JavaScript syntax and features.

**Other alternatives**

If you wanted to test other options, you could consider adding additional benchmark cases that explore different approaches, such as:

* Using property names with bracket notation (e.g., `a['b']`)
* Using the `hasOwnProperty` method to check if a key exists in an object
* Using a custom function or helper to perform property access

However, for this specific benchmark, the focus is on comparing the performance of the `in` operator versus object accessors.

Related benchmarks:

In operator vs Object Accessors (version: 0)

Comparing performance of: in vs Object accessor

Created: 5 years ago by: Guest

Jump to the latest result

in

Object accessor

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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