Benchmark: hasOwnProperty vs index/undefined

Script Preparation code:

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

Tests:

hasOwnProperty successfully, first entry
entries.hasOwnProperty('a')
hasOwnProperty unsuccessfully
entries.hasOwnProperty('f')
index/undefined successfully, first entry
entries['a'] !== undefined
index/undefined unsuccessfully
entries['f'] !== undefined
hasOwnProperty successfully, last entry
entries.hasOwnProperty('e')
index/undefined successfully, last entry
entries['e'] !== undefined

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
hasOwnProperty successfully, first entry
hasOwnProperty unsuccessfully
index/undefined successfully, first entry
index/undefined unsuccessfully
hasOwnProperty successfully, last entry
index/undefined successfully, last entry

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark created using MeasureThat.net. The benchmark tests the performance difference between two approaches: using `hasOwnProperty` to check if an object property exists, and accessing the property directly using square brackets (`[]`). This is done for both the first and last entries in an object.

**Approach 1: Using `hasOwnProperty`**

*   **Pros:** This approach can be more readable and maintainable when working with objects, especially in cases where the property names are not known beforehand. It provides a clear indication of whether the property exists or not.
*   **Cons:** In terms of performance, using `hasOwnProperty` may incur a small overhead due to the additional function call and potential hash table lookup.

**Approach 2: Direct Property Access**

*   **Pros:** This approach is typically faster than using `hasOwnProperty`, as it eliminates the function call overhead and directly accesses the property value.
*   **Cons:** However, this approach can be less readable and maintainable when working with objects, especially if the property names are not known beforehand. It may also lead to runtime errors if the property does not exist.

**Comparison**

The benchmark measures the performance difference between these two approaches for both the first and last entries in the object. The results indicate that direct property access is faster than using `hasOwnProperty`, but only by a small margin.

**Library Usage**

There are no libraries used in this benchmark, so it's purely focused on comparing the performance of two different JavaScript syntaxes.

**Special JS Feature/Syntax**

This benchmark does not use any special JavaScript features or syntax. It's a basic comparison between two common approaches to checking property existence.

**Other Alternatives**

If you're interested in exploring alternative approaches for this type of benchmark, consider using other methods such as:

*   **Using `in` operator**: This can be an alternative to both `hasOwnProperty` and direct property access. The performance difference will likely be similar to that of using `hasOwnProperty`.
*   **Using a library like Lodash's `includes` function**: This can provide a convenient and readable way to check if an object property exists, with the added benefit of being optimized for performance.

Here is a simple example of how you could modify your benchmark to use the `in` operator:

```javascript
// Add this line to the Script Preparation Code:
var entries = {
  // ...
};

// Update Benchmark Definition json to use 'in' operator

[
    {
        "Benchmark Definition": "entries['a'] in entries",
        "Test Name": "hasOwnProperty successfully, first entry"
    },
    {
        "Benchmark Definition": "entries['f'] in entries",
        "Test Name": "hasOwnProperty unsuccessfully"
    }
]
```

Keep in mind that you would need to adjust the script preparation code and other benchmark settings as necessary to accommodate this change.

```javascript
// Modified Benchmark Preparation Code:
var entries = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5
};

// Modify Script Preparation Code to include 'in' operator:
var script = `
if (entries['a'] in entries) {
    // code to execute when condition is true
} else {
    // code to execute when condition is false
}
`;

// Update Html Preparation Code if necessary

```

Latest run results:

Run details: (Test run date: 2025 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

Browser/OS: Chrome 63 on Mac OS X 10.13.3

View result in a separate tab

Test name	Executions per second
hasOwnProperty successfully, first entry	9709318.0 Ops/sec
hasOwnProperty unsuccessfully	9767429.0 Ops/sec
index/undefined successfully, first entry	3424155.0 Ops/sec
index/undefined unsuccessfully	3401654.0 Ops/sec
hasOwnProperty successfully, last entry	9909292.0 Ops/sec
index/undefined successfully, last entry	3425053.2 Ops/sec

Related benchmarks:

hasOwnProperty vs index/undefined (version: 1)

Comparing performance of: hasOwnProperty successfully, first entry vs hasOwnProperty unsuccessfully vs index/undefined successfully, first entry vs index/undefined unsuccessfully vs hasOwnProperty successfully, last entry vs index/undefined successfully, last entry

Created: 6 years ago by: Registered User

Jump to the latest result

hasOwnProperty successfully, first entry

hasOwnProperty unsuccessfully

index/undefined successfully, first entry

index/undefined unsuccessfully

hasOwnProperty successfully, last entry

index/undefined successfully, last entry

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):