Benchmark: undefined checking

Script Preparation code:

var undef;
var x;

Tests:

variable
if(undef !== undefined) {}
x
if(undef !== x) {}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
variable
x

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36

Browser/OS: Chrome 77 on Linux

View result in a separate tab

Test name	Executions per second
variable	3978825.2 Ops/sec
x	5256243.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmark on "undefined checking" using MeasureThat.net. The benchmark tests how different approaches compare in terms of performance when it comes to checking for undefined variables.

**Benchmark Definition Explanation**

The benchmark definition consists of two test cases:

1. `"if(undef !== undefined) {}"`: This test case checks if the variable `undef` is not equal to `undefined`. In JavaScript, this is a common pattern to check if a variable has been declared but not initialized.
2. `"if(undef !== x) {}"`: This test case checks if the variable `undef` is not equal to another variable `x`.

**Comparison of Options**

There are two main approaches being compared:

1. **No explicit check**: In this approach, the code simply checks if a variable has been declared but not initialized by using an implicit check (e.g., assigning the variable without initializing it). This approach relies on JavaScript's optimization mechanisms to detect and throw a `ReferenceError` when trying to access the uninitialized variable.
2. **Explicit undefined check**: In this approach, the code uses an explicit check (e.g., `if(undef !== undefined)` or `if(undefined === undef)` ) to verify that the variable is indeed undefined.

**Pros and Cons of Each Approach**

1. **No explicit check**:
	* Pros:
		+ More concise code
		+ Easier to write and read
	* Cons:
		+ May cause performance issues if not optimized correctly
		+ Can lead to confusing error messages when a `ReferenceError` is thrown
2. **Explicit undefined check**:
	* Pros:
		+ Provides clear indication of whether the variable is initialized or not
		+ Can help avoid runtime errors
	* Cons:
		+ May increase code complexity and verbosity

**Library: None**

There are no external libraries being used in this benchmark.

**Special JS Features/Syntax: None**

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

**Other Considerations**

To get the most accurate results, it's essential to ensure that:

* The code is written with a focus on performance and readability.
* The environment (e.g., browser, device platform, operating system) is consistent across all tests.
* Any optimizations or caching mechanisms are disabled for the benchmark.

**Alternatives**

If you need more control over your JavaScript benchmarks, consider using alternative tools such as:

* Node.js's built-in `perf_hooks` module
* Benchmarking libraries like `benchmarkjs` or `speedtest`
* WebAssembly-based benchmarking tools like `wasm-benchmark`

Keep in mind that each tool has its strengths and weaknesses, and the choice of tool ultimately depends on your specific use case and requirements.

Related benchmarks:

undefined checking (version: 0)

Comparing performance of: variable vs x

Created: 5 years ago by: Guest

Jump to the latest result

variable

x

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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