Benchmark: ! syntax vs === undefined

Script Preparation code:

var obj = {}

Tests:

"!" syntax
if (!obj["a"]) { console.log("object property not found") };
object.property === undefined
if (obj["a"] === undefined) { console.log("object property not found") };

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:

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark definition and test cases.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches:

1. Using the `!` syntax to check if an object property exists, e.g., `if (!obj["a"])`.
2. Checking if an object property is equal to `undefined`, e.g., `if (obj["a"] === undefined)`.

**Options Compared**

The benchmark compares these two approaches on a single test case, where the object `obj` does not have a property named `"a"`. The goal is to determine which approach is faster and more efficient.

**Pros and Cons of Each Approach**

1. **! syntax**
	* Pros: Can be faster for non-strict equality checks (e.g., when checking if a value is null or undefined).
	* Cons: May not work as expected in strict modes, where `!` has a different meaning.
2. **object.property === undefined**
	* Pros: Works consistently across all JavaScript implementations and modes.
	* Cons: May be slower than the `!` syntax for non-strict equality checks.

**Library and Special JS Feature**

There is no specific library used in this benchmark, but it does use a feature of the JavaScript language called the "optional chaining operator" (`?.`). However, since we're not using any modern features or transpilation, this feature won't be relevant. Also, note that `!` has been recognized as a valid operator for null coalescing in ECMAScript 2022.

**Other Considerations**

The benchmark only tests two specific scenarios and doesn't cover all possible cases where these approaches might differ. For example, it doesn't test what happens when the object property is set to `null` or a falsy value (e.g., `undefined`, `false`, `0`, etc.).

**Alternatives**

If you were to create your own benchmark for comparing these two approaches, you could also consider testing:

* Using `in` operator (`obj["a"] in obj`) instead of the `!` syntax or property equality check.
* Comparing performance with different data types (e.g., strings, numbers, booleans).
* Testing multiple iterations of each approach to see if consistency is achieved.

Keep in mind that the `!` syntax and the `object.property === undefined` approach are not always equivalent due to differences in implementation across browsers or older JavaScript versions.

Related benchmarks:

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

comparing ! object property vs object property === undefined

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

Created: 4 years ago by: Guest

Jump to the latest result

"!" syntax

object.property === undefined

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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