Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty my 4

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

Tests:

ue
undefined !== obj.d;
aue
'undefined' !== typeof obj.d;
eu
undefined !== obj.xxxd;
eau
'undefined' !== typeof obj.xxxd;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
ue
aue
eu
eau

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested, compared, and some of the considerations.

**Benchmark Definition**

The benchmark is designed to test object lookup performance using four different methods:

1. `undefined`
2. `typeof` with a string literal
3. `in` operator
4. `hasOwnProperty`

These methods are all used to access properties on an object (`obj`) that contains 5 properties: `a`, `b`, `c`, `d`, and `e`. The benchmark is interested in the lookup performance of each method.

**Options Compared**

Here's a brief explanation of what's being compared:

* `undefined`: Using the value `undefined` to access an object property. This is likely being used to test if the object has the property, but since it's set to `undefined`, this will always return false.
* `typeof obj.d`: Using the `typeof` operator to check the type of `obj.d`. Since `d` is a string, this will return `'string'`.
* `in`: Using the `in` operator to check if the object has the property. This operator returns a boolean value indicating whether the property exists.
* `hasOwnProperty`: Using the `hasOwnProperty` method on the object to check if it owns the property. This method returns a boolean value indicating whether the property is an own property of the object.

**Pros and Cons**

Here are some pros and cons for each approach:

* `undefined`: Pros: None. Cons: The lookup will always return false, which may not accurately represent real-world usage.
* `typeof obj.d`: Pros: Returns a string indicating the type of `obj.d`. Cons: May have performance overhead due to the type check.
* `in`: Pros: Fast and efficient for checking property existence. Cons: May not be as precise as other methods since it only checks if the property exists, not its value.
* `hasOwnProperty`: Pros: Returns a boolean indicating whether the property is an own property of the object. Cons: May have performance overhead due to the method call.

**Library Usage**

There are no libraries explicitly mentioned in this benchmark definition. However, the use of `typeof` and `in` operators suggests that JavaScript's built-in type system and operator overloads are being utilized.

**Special JS Features/Syntax**

The benchmark does not specifically test any special JavaScript features or syntax beyond what is already covered by the `typeof`, `in`, and `hasOwnProperty` methods. However, it does utilize some advanced concepts like object literals and property access.

**Alternatives**

Other alternatives for testing object lookup performance might include:

* Using a different data structure, such as an array or set.
* Testing the performance of multiple property accesses in a row.
* Using a different language or platform to test compatibility with this benchmark.

Keep in mind that these alternatives would require significant changes to the benchmark definition and setup.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.192 Safari/537.36

Browser/OS: Chrome 88 on Windows

View result in a separate tab

Test name	Executions per second
ue	2834280.8 Ops/sec
aue	8165213.5 Ops/sec
eu	2850036.0 Ops/sec
eau	7893338.5 Ops/sec

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty my 4 (version: 0)

Object lookup performance

Comparing performance of: ue vs aue vs eu vs eau

Created: 4 years ago by: Guest

Jump to the latest result

ue

aue

eu

eau

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):