Benchmark: Testing for false vs === undefined vs hasOwnProperty for undefined member vs hasown

Tests:

test truth
var n = {}; while(true) { if(!n.foo) break; }
test undefined
var n = {}; while(true) { if(n.foo===undefined) break; }
test hasOwnProperty
var n = {}; while(true) { if(!n.hasOwnProperty('foo')) break; }
test hasown
var n = {}; while(true) { if(!Object.hasOwn(n,'foo')) break; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
test truth
test undefined
test hasOwnProperty
test hasown

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark JSON and explain what's being tested, compared, and other considerations.

**Overview**

The MeasureThat.net website allows users to create and run JavaScript microbenchmarks. The benchmark in question tests four different approaches for checking if an object property exists or is undefined:

1. `!n.foo` (negation of existence)
2. `n.foo === undefined`
3. `n.hasOwnProperty('foo')`
4. `Object.hasOwn(n, 'foo')`

**Test Cases**

Each test case is defined by a benchmark definition script and a test name. The scripts are designed to create an object `n` with no properties.

1. **test truth**: This test case uses the negation of existence (`!n.foo`) to check if `n.foo` exists. It enters a loop that breaks when `n.foo` is falsy (i.e., `undefined`, `null`, or `false`). The purpose of this test is likely to measure the performance difference between using negation and equality checks.
2. **test undefined**: This test case uses equality with `undefined` (`n.foo === undefined`) to check if `n.foo` exists. It enters a loop that breaks when `n.foo` is equal to `undefined`. The purpose of this test is likely to measure the performance difference between using equality checks and negation.
3. **test hasOwnProperty**: This test case uses the `hasOwnProperty()` method to check if `n` has a property named `'foo'`. It enters a loop that breaks when `n.hasOwnProperty('foo')` returns `false`.
4. **test hasown**: This test case uses the `Object.hasOwn()` method to check if `n` has an own property named `'foo'`. It enters a loop that breaks when `Object.hasOwn(n, 'foo')` returns `false`.

**Libraries and Special JS Features**

None of the benchmark definitions use any libraries or special JavaScript features. However, it's worth noting that some of these methods (e.g., `hasOwnProperty()`, `Object.hasOwn()`) are part of the ECMAScript standard and can be used across different browsers and environments.

**Pros and Cons of Each Approach**

Here's a brief summary of the pros and cons of each approach:

1. **!n.foo**: This approach is simple and widely supported, but it may not work as expected in some cases (e.g., when `n` is an array or an object with a prototype).
2. **n.foo === undefined**: This approach is more explicit and accurate than negation, but it can be slower due to the equality check.
3. **n.hasOwnProperty('foo')**: This approach is specific to objects and has its own set of nuances (e.g., it returns `false` when `n` has a property with the same name but different value). It's generally faster than using negation or equality checks.
4. **Object.hasOwn(n, 'foo')**: Similar to `hasOwnProperty()`, this approach is specific to objects and can be slower due to the extra indirection.

**Other Considerations**

* The benchmark may not accurately represent real-world scenarios where property existence is crucial.
* The use of `while` loops instead of more modern approaches (e.g., using `for...in`) might introduce unnecessary complexity or performance overhead.
* The tests do not account for edge cases like null or undefined values being assigned to properties.

**Alternatives**

If you were to reimplement these benchmarks, consider the following alternatives:

1. **Use a more modern approach**: Instead of using `while` loops and negation, consider using `for...in` loops or modern approaches that leverage the `hasOwnProperty()` method.
2. **Account for edge cases**: Add tests to cover scenarios where property existence is crucial (e.g., assigning null or undefined values to properties).
3. **Use a more precise equality check**: Instead of relying on negation or equality checks, consider using a more explicit approach like `n.foo === undefined` or `Object.is(n.foo, undefined)`.

Keep in mind that these alternatives are speculative, and the original benchmarks might be optimized for specific use cases or performance characteristics.

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Windows

View result in a separate tab

Test name	Executions per second
test truth	92841448.0 Ops/sec
test undefined	5950026.5 Ops/sec
test hasOwnProperty	48999452.0 Ops/sec
test hasown	5378097.0 Ops/sec

Related benchmarks:

Testing for false vs === undefined vs hasOwnProperty for undefined member vs hasown (version: 0)

Comparing performance of: test truth vs test undefined vs test hasOwnProperty vs test hasown

Created: 8 months ago by: Guest

Jump to the latest result

test truth

test undefined

test hasOwnProperty

test hasown

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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