Benchmark: Option chaining and typeof 2

Script Preparation code:

window._x = { y: 4 };
window._z = null;

Tests:

Optional chaining, not null
let a = typeof (_x === null || _x === void 0 ? void 0 : _x.y) === `number`;
Explicit null check, not null
let a = _x != null && typeof _x.y === `number`;
Optional chaining, null
let a = typeof (_z === null || _z === void 0 ? void 0 : _z.y) === `number`;
Explicit null check, null
let a = _z != null && typeof _z.y === `number`;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Optional chaining, not null
Explicit null check, not null
Optional chaining, null
Explicit null check, null

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmark that tests the performance of two different approaches to check if an object has a certain property and its value is a specific type.

**Benchmark Definition**

The benchmark definition is:

```
let a = typeof (_x === null || _x === void 0 ? void 0 : _x.y) === `number`;
```

This line checks if the property `y` of an object `_x` exists and its value is a string that equals "number". The optional chaining operator (`?.`) is used to access the `y` property without throwing an error if it doesn't exist.

There are four test cases:

1. **Optional Chaining, Not Null**: Checks if the `y` property of `_x` exists and its value is a string that equals "number".
2. **Explicit Null Check, Not Null**: Uses an explicit null check (`_x != null`) to access the `y` property.
3. **Optional Chaining, Null**: Checks if the `y` property of an object with `null` value exists and its value is a string that equals "number".
4. **Explicit Null Check, Null**: Uses an explicit null check (`_z != null`) to access the `y` property.

**Libraries and Special Features**

There is no library used in this benchmark. However, there are some special features:

* The optional chaining operator (`?.`) was introduced in JavaScript with the release of ECMAScript 2020 (ES2020). It allows you to access nested properties without throwing an error if a null or undefined value is encountered.
* The `void 0` expression is used to achieve null coalescing, which is also a new feature introduced in ES2020.

**Approach Comparison**

The benchmark compares the performance of two approaches:

1. **Optional Chaining**: Uses the optional chaining operator (`?.`) to access nested properties without checking for null or undefined values.
2. **Explicit Null Check**: Uses explicit checks (`_x != null` or `_z != null`) to ensure that the object exists before accessing its properties.

**Pros and Cons of Each Approach**

* **Optional Chaining**:
	+ Pros: More concise, readable code; avoids unnecessary checks.
	+ Cons: May be slower due to the additional complexity introduced by the optional chaining operator.
* **Explicit Null Check**:
	+ Pros: Can be faster since it only checks for null or undefined values once.
	+ Cons: Requires more code and can make the syntax less concise.

**Other Considerations**

* The benchmark uses Chrome 108 as the browser, which may affect the results due to differences in JavaScript engine optimizations between browsers.
* The `DevicePlatform` and `OperatingSystem` fields are not relevant to the performance comparison but provide additional metadata about the test environment.
* The `ExecutionsPerSecond` field provides a measure of the benchmark's execution frequency, which can be used to compare the performance across different browsers or versions.

**Alternatives**

Some possible alternatives to this benchmark could include:

* Testing other ways to check for null or undefined values, such as using the `??` operator (nullish coalescing) or explicit checks with `in` operator.
* Comparing the performance of optional chaining with explicit null checking in different browsers or versions.
* Using a more comprehensive test suite that covers various use cases and edge scenarios.

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/108.0.0.0 Safari/537.36 Edg/108.0.1462.54

Browser/OS: Chrome 108 on Windows

View result in a separate tab

Test name	Executions per second
Optional chaining, not null	2379731.0 Ops/sec
Explicit null check, not null	3700637.8 Ops/sec
Optional chaining, null	6561355.0 Ops/sec
Explicit null check, null	6688356.0 Ops/sec

Related benchmarks:

Option chaining and typeof 2 (version: 0)

Comparing performance of: Optional chaining, not null vs Explicit null check, not null vs Optional chaining, null vs Explicit null check, null

Created: one year ago by: Guest

Jump to the latest result

Optional chaining, not null

Explicit null check, not null

Optional chaining, null

Explicit null check, null

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):