Benchmark: if (!x) syntax vs if (x === undefined)

Script Preparation code:

var obj = {}

Tests:

"!" syntax
if (!obj["a"]) { return false };
object.property === undefined
if (obj["a"] === undefined) { return false };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
"!" syntax
object.property === undefined

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.71 Safari/537.36

Browser/OS: Chrome 97 on Windows

View result in a separate tab

Test name	Executions per second
"!" syntax	15239805.0 Ops/sec
object.property === undefined	5582312.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Definition JSON**

The benchmark is defined by a single JSON object that contains:

* `Name`: a descriptive name for the benchmark
* `Description`: a brief explanation of what the benchmark is testing
* `Script Preparation Code` and `Html Preparation Code`: these are code snippets that will be executed before running each test case

In this case, the script preparation code simply creates an empty object `var obj = {}`.

**Individual Test Cases**

There are two test cases defined:

1. **"!\" syntax"`:
	* The benchmark definition is: `if (!obj["a"]) { return false };`
	* This test case checks how JavaScript handles the conditional operator (`!`) when used with an object property.
2. **"object.property === undefined"`:
	* The benchmark definition is: `if (obj["a"] === undefined) { return false };`
	* This test case checks how JavaScript compares an object property to `undefined` using the equality operator (`===`).

**Comparison of Options**

In both cases, we have two options:

1. **"!\" syntax"`:
	* Pros: concise and easy to read.
	* Cons: may not be as intuitive or readable for some developers (especially those from other languages).
2. **"object.property === undefined"`:
	* Pros: explicit and clear in its intent, making it easier to understand for others.
	* Cons: slightly longer than the first option.

**Libraries Used**

None are explicitly mentioned in the benchmark definition or test cases.

**Special JavaScript Features or Syntax**

There's no mention of any special features or syntax beyond what's already described.

**Other Considerations**

This benchmark seems to focus on comparing different approaches for handling conditional expressions with object properties. The use of `!` and `=== undefined` both provide valid ways to achieve the same result, but with different characteristics (readability, conciseness, etc.).

**Alternatives**

If you wanted to explore alternatives, you could try:

* Using template literals or string concatenation instead of conditional expressions.
* Implementing a custom function for checking object property existence.
* Comparing performance with other programming languages or engines.

Some possible additional test cases that might be interesting:

* Using `in` operator (`obj["a"] in obj`) instead of `!` and `=== undefined`.
* Checking the impact of using strict mode (e.g., `if (!obj["a"]) { ... }` instead of `if (!obj["a"]))` on performance.
* Comparing different browsers' handling of these conditional expressions.

Feel free to add or modify test cases as you see fit!

Related benchmarks:

if (!x) syntax vs if (x === undefined) (version: 0)

comparing ! object property vs object property === undefined

Comparing performance of: "!" syntax vs object.property === undefined

Created: 2 years ago by: Guest

Jump to the latest result

"!" syntax

object.property === 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):