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

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; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
test truth
test undefined
test hasOwnProperty

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
test truth	157604176.0 Ops/sec
test undefined	15435528.0 Ops/sec
test hasOwnProperty	92550024.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**What is being tested?**

The provided JSON represents three microbenchmarks that test the performance differences between using `===` with `undefined`, `hasOwnProperty()` with `undefined`, and replacing `=== undefined` with a logical test.

In essence, these benchmarks aim to determine if there's a performance benefit to replacing the traditional way of checking for the absence of a property (`n.foo === undefined`) with more efficient alternatives.

**Options being compared:**

1. **Traditional approach:** `if (n.foo === undefined) { ... }`
2. **hasOwnProperty() approach:** `if (!n.hasOwnProperty('foo')) { ... }`
3. **Logical test approach:** `if (!n.foo) { ... }` (replacing `=== undefined` with a logical negation)

**Pros and Cons of each approach:**

1. **Traditional approach:**
	* Easy to read and understand
	* May be slower due to the unnecessary comparison
	* Does not account for the presence of other properties in the object
2. **hasOwnProperty() approach:**
	* More efficient, as it only checks if the property exists in the object's prototype chain
	* May be slower for objects with many properties
	* Less intuitive than the traditional approach
3. **Logical test approach:**
	* Most efficient, as it avoids the unnecessary comparison and directly checks for the absence of a property
	* Least intuitive due to its unconventional syntax

**Library usage:**

None of the benchmarks appear to use any external libraries.

**Special JavaScript features or syntax:**

The `hasOwnProperty()` method is a built-in JavaScript method that checks if an object has a given property. The logical test approach uses the unary negation operator (`!`) to negate the result of the property check, which is a common idiom in JavaScript.

**Other considerations:**

* These benchmarks only consider the performance difference between these three approaches and do not take into account other factors that may affect performance, such as object creation or iteration.
* The use of `=== undefined` is generally discouraged in modern JavaScript code, as it can lead to confusing and unexpected behavior. The logical test approach provides a more concise and expressive way to achieve the same result.

**Alternatives:**

Other alternatives for checking if a property exists or not include:

1. Using the `in` operator: `if ('foo' in n) { ... }`
2. Using the `for...in` loop with `hasOwnProperty()`: `for (var prop in n) { if (n.hasOwnProperty(prop)) { ... } }`
3. Using a more modern approach with destructuring or optional chaining (`?.`): `if (!n.foo) { ... }`

These alternatives may have their own trade-offs and considerations, depending on the specific use case and requirements.

Related benchmarks:

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

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

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

Created: 8 years ago by: Guest

Jump to the latest result

test truth

test undefined

test hasOwnProperty

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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