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

Script Preparation code:

var n = {};
var unde = undefined;

Tests:

test truthyness
while (true) { if (!n.foo) break; }
test undefined
while (true) { if (n.foo === unde) break; }
test hasOwnProperty
while (true) { if (!n.hasOwnProperty('foo')) break; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
test truthyness
test undefined
test hasOwnProperty

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

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Let's dive into the Benchmark Definition json and explain what is being tested.

**What is being tested?**

The benchmark is designed to compare three different approaches:

1. Using `!n.foo` (logical NOT)
2. Using `=== undefined` (strict equality check with `undefined`)
3. Using `.hasOwnProperty('foo')` (a method call on the object)

These approaches are used in a simple while loop that breaks when `n.foo` is falsy.

**Options compared**

The benchmark is comparing the performance of these three approaches:

1. **Logical NOT (`!n.foo`)**: This approach uses the logical NOT operator, which negates the value of `n.foo`. This can be an efficient way to check if a property exists or not, as it avoids the overhead of method calls.
2. **Strict equality check with `undefined` (`=== undefined`)**: This approach explicitly checks if `n.foo` is equal to `undefined`, which can be slower than using logical NOT.
3. **Method call on `hasOwnProperty` (`.hasOwnProperty('foo')`)**: This approach uses the `hasOwnProperty` method, which is a built-in method that returns `true` if an object has the specified property as its own property, rather than inheriting it from its prototype chain.

**Pros and Cons of each approach**

1. **Logical NOT (`!n.foo`)**:
	* Pros: fast, efficient, and concise.
	* Cons: may not be immediately obvious to developers who are not familiar with JavaScript's truthy/falsy behavior.
2. **Strict equality check with `undefined` (`=== undefined`)**:
	* Pros: explicit and clear, can help avoid unexpected results due to inheritance or prototype chain issues.
	* Cons: slower than logical NOT due to the extra step of checking for equality.
3. **Method call on `hasOwnProperty` (`.hasOwnProperty('foo')`)**:
	* Pros: avoids potential pitfalls related to inheritance and prototype chains, can be more readable in some cases.
	* Cons: slower than logical NOT and strict equality checks.

**Library/External feature**

There is no external library used in this benchmark. However, the use of `=== undefined` might require a basic understanding of JavaScript's type system and equality checks.

**Special JS features or syntax**

None mentioned explicitly, but the use of logical NOT (`!n.foo`) relies on an understanding of JavaScript's truthy/falsy behavior, which can be a nuanced topic.

Now that we've discussed the benchmark, here are some alternative approaches you could consider:

1. Use `Object.hasOwn(n, 'foo')`: This method is similar to `.hasOwnProperty`, but it takes two arguments: the object and the property name.
2. Use `n.foo !== undefined`: This approach is similar to using `=== undefined`, but it's often considered more idiomatic in modern JavaScript code.
3. Use a custom implementation of `hasOwnProperty` or a library like Lodash, which provides a more expressive and efficient way to check for property existence.

Keep in mind that these alternatives might not provide significant performance benefits over the original benchmark, as they are generally optimized by modern JavaScript engines.

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 truthyness vs test undefined vs test hasOwnProperty

Created: 8 years ago by: Guest

Jump to the latest result

test truthyness

test undefined

test hasOwnProperty

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):