Benchmark: Testing for false vs === undefined

Tests:

test truth
var n = undefined; while(true) { if(!n) break; }
test undefined
var n = undefined; while(true) { if(n===undefined) break; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
test truth
test undefined

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; Trident/7.0; rv:11.0) like Gecko

Browser/OS: IE 11 on Windows

View result in a separate tab

Test name	Executions per second
test truth	19282794.0 Ops/sec
test undefined	10577857.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

The provided JSON represents a benchmark test that compares two approaches to checking if a variable is `undefined`. The goal is to determine whether using a logical test (`!n`) or the exact equality check (`n === undefined`) has a performance benefit.

**Approach 1: Using a logical test (`!n`)**

In this approach, we're using a negation operator (`!`) to invert the value of `n`. If `n` is `undefined`, `!n` becomes `true`, and vice versa. This allows us to use a simple boolean condition to break out of the loop.

**Approach 2: Exact equality check (`n === undefined`)**

In this approach, we're directly comparing `n` with `undefined`. If they match, we can exit the loop.

**Pros and Cons**

* **Logical test (`!n`)**
	+ Pros:
		- More concise and readable code.
		- Less likely to introduce errors due to typos or off-by-one errors.
	+ Cons:
		- May not be as efficient as exact equality checks, especially in older browsers.
		- Can lead to unexpected behavior if `n` is a falsy value (e.g., `0`, `""`, `null`, etc.).
* **Exact equality check (`n === undefined`)**
	+ Pros:
		- More explicit and predictable behavior.
		- May be faster than logical tests, especially in modern browsers.
	+ Cons:
		- Less concise code compared to the logical test.
		- More prone to errors due to typos or off-by-one errors.

**Other Considerations**

* The use of `===` (strict equality) is generally considered better practice than `==` (loose equality), as it avoids unexpected behavior with different data types.
* In modern JavaScript, the ` === ` and ` !== ` operators are also optimized for performance, making exact equality checks even faster.

**Library**

None in this specific benchmark. The test only relies on standard JavaScript features.

**Special JS Feature/Syntax**

There is no special feature or syntax used in this benchmark that requires explanation.

Now, let's look at the individual test cases:

1. `test truth`:
	* This test uses a logical test (`!n`) to check if `n` is `undefined`. The loop breaks when `!n` becomes `true`, indicating that `n` has been set to an invalid value.
2. `test undefined`:
	* This test uses an exact equality check (`n === undefined`) to verify that `n` is indeed `undefined`.

**Alternatives**

If you want to explore more performance-related JavaScript benchmarks, here are some alternatives:

1. **Micro-benchmarking frameworks**: Tools like Benchmark.js or jsperf provide a structured approach to benchmarking different JavaScript features and libraries.
2. **JavaScript performance comparison sites**: Websites like JsPerf or Benchmarking.net allow you to compare the performance of different JavaScript implementations (e.g., V8, SpiderMonkey) on various platforms.
3. **Benchmarking libraries for specific use cases**: Libraries like Lodash or Ramda provide optimized algorithms and benchmarks for common tasks, such as string manipulation or functional programming.

Keep in mind that micro-benchmarking can be an art more than a science, and results may vary depending on the JavaScript engine, browser, and platform being tested.

Related benchmarks:

Testing for false vs === undefined (version: 0)

Is there a performance benefit to replacing === undefined with a logical test?

Comparing performance of: test truth vs test undefined

Created: 7 years ago by: Guest

Jump to the latest result

test truth

test undefined

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):