Benchmark: hasOwnProperty vs Object.keys (longer)

Script Preparation code:

var props = {a:1,b:1,c:1,d:1,e:1,f:1,g:1,h:1,i:1,j:1,k:1,l:1,m:1,n:1,o:1,p:1,q:1,r:1,s:1,t:1,u:1,v:1,w:1,x:1,y:1,z:1};
for (var i=0;i<1000;i++){
  var key = i.toString();
  props[i]=i;
}

Tests:

hasOwnProperty
for (var p in props) { if (Object.prototype.hasOwnProperty.call(props, p)) { props[p] = 2; } }
Object.keys
for (var k=Object.keys(props), l=k.length, i=0; i<l; i++) { props[k[i]] = 2; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
hasOwnProperty
Object.keys

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36 Edg/134.0.0.0

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
hasOwnProperty	46482.7 Ops/sec
Object.keys	100873.3 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

### Benchmark Overview

The benchmark defined in the provided JSON is meant to compare two different methods of iterating over properties of an object in JavaScript. Specifically, it tests:

1. **Using `hasOwnProperty` for property checks**
2. **Using `Object.keys` to retrieve property keys**

### Description of Options Compared

#### 1. **Using `hasOwnProperty`**

- **Benchmark Code:**
    ```javascript
    for (var p in props) {
      if (Object.prototype.hasOwnProperty.call(props, p)) {
        props[p] = 2;
      }
    }
    ```

- **Summary of Approach:**
   - This approach uses a `for...in` loop to iterate over all enumerable properties of an object (`props`).
   - The `hasOwnProperty` method is employed to check whether the property belongs to the object directly and is not inherited.

- **Pros:**
  - Can iterate over all enumerable properties, including those added after object creation.
  - Useful in cases where object prototypes are extended.

- **Cons:**
  - Slower due to the need to perform a call to `hasOwnProperty` for each iteration.
  - The `for...in` loop also iterates over inherited properties unless filtered by `hasOwnProperty`, which can lead to potential bugs or performance issues if not handled.

#### 2. **Using `Object.keys`**

- **Benchmark Code:**
    ```javascript
    for (var k = Object.keys(props), l = k.length, i = 0; i < l; i++) {
      props[k[i]] = 2;
    }
    ```

- **Summary of Approach:**
   - This method leverages `Object.keys`, which returns an array of the object’s own enumerable property names.
   - It uses a traditional `for` loop to iterate through the array of keys.

- **Pros:**
  - Typically faster than the `hasOwnProperty` method since it does not include the overhead of additional checks in each iteration.
  - Returns only the object's own properties, avoiding the potential pitfalls of inherited properties.

- **Cons:**
  - Requires the creation of an array of keys, which uses additional memory.
  - If the object is very large, this could also introduce a performance hit due to array creation time.

### Library and Syntax Features Used

In this benchmark, no specific external libraries are used—everything operates within native JavaScript functionality. The benchmark primarily relies on core language features such as objects and iteration constructs.

### Benchmark Results

From the latest benchmark results, we observe that:

- **`Object.keys`**: Executed at approximately **100,873** operations per second.
- **`hasOwnProperty`**: Executed at approximately **46,483** operations per second.

### Considerations and Alternatives

The benchmark clearly shows that using `Object.keys` is significantly faster than using `hasOwnProperty` with a `for...in` loop for checking object properties.

**Other Alternatives:**
1. **`Object.entries`**: This would provide an array of key-value pairs for both own properties and could be used in a similar loop structure.
  
2. **`Map` Objects**: If you require a more efficient way to manage key-value pairs without the concerns of inheritance, using a `Map` object might be preferable.

3. **`forEach` method**: If you are leveraging arrays (after getting keys using `Object.keys`), you could also consider using the `.forEach()` method for clearer and more expressive code.

Overall, the decision between these methods should take into account the specific requirements of your code (e.g., speed vs memory efficiency) and the context in which they are implemented.

Related benchmarks:

hasOwnProperty vs Object.keys (longer) (version: 1)

Comparing performance of: hasOwnProperty vs Object.keys

Created: one month ago by: Guest

Jump to the latest result

hasOwnProperty

Object.keys

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):