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

Script Preparation code:

var n = {};

Tests:

test truthyness
!n.foo
test undefined
n.foo === undefined
test hasOwnProperty
!n.hasOwnProperty('foo')

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

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**Benchmark Definition**

The benchmark is defined as: "Testing for false vs === undefined vs hasOwnProperty for undefined member".

This means that we're trying to determine if there's a performance difference between three different approaches:

1. `false` (no test at all)
2. `=== undefined` (testing if the property exists or not)
3. `.hasOwnProperty('foo')` (checking if the object has the property 'foo')

**Approach 1: `false`**

This approach does nothing, which is likely to be the fastest but also least informative.

Pros: Fastest
Cons: Least useful for understanding performance impact

**Approach 2: `=== undefined`**

This approach uses a logical test to check if the property exists. The syntax `x === undefined` checks if the value of the property `foo` is `undefined`.

In JavaScript, `===` checks both value and type equality. Since `undefined` is a primitive value, this comparison works as expected.

Pros: Simple and straightforward
Cons: May have performance overhead due to the logical test

**Approach 3: `.hasOwnProperty('foo')`**

This approach uses a method call on the object `n` to check if it has the property 'foo'. The syntax `.hasOwnProperty('foo')` returns `true` if the object has the property, and `false` otherwise.

Pros: More readable than logical tests
Cons: May have performance overhead due to the method call

**Library usage**

In this benchmark, no specific library is used beyond the built-in JavaScript methods (`===`, `.hasOwnProperty()`).

**Special JS features or syntax**

The benchmark uses the following special JavaScript features:

1. `!` (logical NOT operator): Used in `!n.foo` to negate the property existence test.
2. `.foo` and `.bar` properties on object `n`: These are being used to create a simple object with an undefined property.

These features are essential for creating the benchmark's test cases.

**Other alternatives**

If we were to use alternative approaches, we could consider:

1. Using a more explicit or efficient way to check property existence, such as using `in` operator.
2. Using a different comparison method, such as comparing the value with `NaN`.
3. Using a mock object or a proxy object to control the behavior of the benchmark.

However, these alternatives would likely change the focus of the benchmark and might not provide a clear answer to the original question.

Overall, the benchmark provides a simple yet informative test case for evaluating the performance impact of different approaches to checking property existence in JavaScript.

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko

Browser/OS: IE 11 on Windows 7

View result in a separate tab

Test name	Executions per second
test truthyness	16524795.0 Ops/sec
test undefined	9385663.0 Ops/sec
test hasOwnProperty	14245664.0 Ops/sec

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: 7 years ago by: Guest

Jump to the latest result

test truthyness

test undefined

test hasOwnProperty

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):