Benchmark: Testing for false vs undefined vs == null vs prototype.hasOwnProperty vs hasOwn for undefined member

Testing for false vs undefined vs == null vs prototype.hasOwnProperty vs hasOwn for undefined member (version: 0)

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

Comparing performance of: test false vs test undefined vs test hasOwnProperty vs test == null vs test == undefined vs test static hasOwnProperty vs test static hasOwn

Created: 4 years ago by: Registered User

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Tests:

test false
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 == null
var n = {}; while(true) { if(n.foo==null) break; }
test == undefined
var n = {}; while(true) { if(n.foo==undefined) break; }
test static hasOwnProperty
var n = {}; while(true) { if(!Object.prototype.hasOwnProperty(n,'foo')) break; }
test static 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 false
test undefined
test hasOwnProperty
test == null
test == undefined
test static hasOwnProperty
test static hasOwn

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the test cases and the options being compared.

**What is tested?**

The benchmark tests different ways to check if a property exists on an object. The properties being checked are `foo`, `bar` (not mentioned in the provided benchmark definition, but present in some test cases), and other special values like `undefined`, `null`, and `undefined member`.

**Options compared:**

1. **Simple `!property_exists`**: Directly checks if a property exists using the `in` operator or the `hasOwnProperty` method.
2. **Logical tests**: Replaces `== null` with a logical test `!(property_value === null)` to check if a value is not equal to `null`.
3. **Logical tests for `undefined`**: Replaces `== undefined` with a logical test `(property_value !== undefined)`, but since `undefined` is not a number, this test might behave unexpectedly.
4. **Static `hasOwnProperty`**: Uses the static method `Object.prototype.hasOwnProperty.call(obj, prop)` to check if a property exists on an object.
5. **Dynamic `hasOwn`**: Uses the non-static method `Object.hasOwn(obj, prop)` to check if a property exists on an object.

**Pros and Cons:**

1. **Simple `!property_exists`**:
	* Pros: Lightweight, easy to understand, and works well for most use cases.
	* Cons: May be slower due to the overhead of the `in` operator or `hasOwnProperty` method.
2. **Logical tests**:
	* Pros: Can be more readable and expressive than simple checks, especially for cases where a value might be an empty string or an empty object.
	* Cons: May not work as expected for certain types (e.g., `undefined`), and can lead to confusing code if not used carefully.
3. **Logical tests for `undefined`**:
	* Pros: None notable, as this test is less relevant due to the nuances of JavaScript's `undefined` type.
	* Cons: May still produce unexpected results due to the nature of `undefined`.
4. **Static `hasOwnProperty`**:
	* Pros: More efficient than non-static methods, works well for most cases, and is a standard part of the JavaScript API.
	* Cons: Requires an extra call to check if the object has the property, which might be slower in some cases.
5. **Dynamic `hasOwn`**:
	* Pros: Similar to static `hasOwnProperty`, but with better support for objects that may not have the prototype chain defined.
	* Cons: Less efficient than static methods due to the overhead of the dynamic method.

**Other considerations:**

1. **Use cases:** Logical tests are often used when working with values that might be empty or have a specific meaning in your application (e.g., "is this value a valid email address?"). However, for simple property existence checks, `!property_exists` is usually sufficient.
2. **Best practices:** Avoid using logical tests with `== null`, as they can lead to confusion and unexpected results. Instead, use the simpler `!= null` check or directly compare with `null`.
3. **JavaScript version support:** Some older browsers might not support certain methods (e.g., `hasOwn`), so consider this when choosing an approach.

In conclusion, while there are pros and cons to each option, `!property_exists` remains the most straightforward and efficient choice for simple property existence checks. However, logical tests can be useful in specific scenarios where readability and expressiveness are important.

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