Benchmark: for-in-hasOwnProperty vs object.keys-direct

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in-hasOwnProperty
for (var i=10000; i > 0; i--) { for (var key in obj) { if(obj.hasOwnProperty(key)) { console.log(key); } } }
Object.keys-direct
for (var i=10000; i > 0; i--) { var keys = Object.keys(obj); for(var j = 0, l = keys.length; j < l; j++) { console.log(keys[j]); } }
Object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(key)); }
for-in
for (var i=10000; i > 0; i--) { for (var key in obj) { console.log(key); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in-hasOwnProperty
Object.keys-direct
Object.keys
for-in

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):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Overview**

The provided benchmark tests four different ways to iterate over the properties of an object in JavaScript: `for-in`, `hasOwnProperty` with `in`, `Object.keys`, and a direct call to `Object.keys`. The benchmark consists of 100,000 iterations for each test case.

**Options Compared**

Here's a brief overview of what's being tested:

1. **`for-in`**: This method uses the `in` operator to iterate over an object's properties. It also checks if the property is a direct own property using the `hasOwnProperty` method.
2. **`hasOwnProperty` with `in`**: This approach combines the benefits of both methods: it checks for `hasOwnProperty` before iterating, but still uses `in` to get the property names.
3. **`Object.keys`**: This method returns an array of a given object's own enumerable property names. It doesn't provide any iteration functionality, so we need to call `forEach`, `map`, or use a loop to iterate over the properties.
4. **Direct `Object.keys` call**: Similar to the previous point, but it simply calls `Object.keys` and then iterates over the returned array using `forEach`.

**Pros and Cons**

Here's a brief summary of each approach:

1. **`for-in`**:
	* Pros: Native performance, easy to read and write.
	* Cons: May not work correctly for non-enumerable properties, can be slow if iterating over all properties.
2. **`hasOwnProperty` with `in`**:
	* Pros: Combines the benefits of both methods, slightly faster than `for-in`.
	* Cons: Requires additional checks, may not be as readable as other options.
3. **`Object.keys`**:
	* Pros: Provides a clear and explicit way to get property names, can be used with various iteration methods.
	* Cons: May incur a slight performance overhead due to the array creation, requires more code than `for-in`.
4. **Direct `Object.keys` call**:
	* Pros: Similar to `Object.keys`, but without the extra overhead of calling it and then iterating.
	* Cons: Requires additional iteration logic, may be less readable.

**Other Considerations**

When choosing an iteration method, consider the following factors:

* Performance: If speed is critical, `for-in` might be a better choice. However, if you're working with large datasets or need more explicit control over iteration, other methods might be more suitable.
* Readability: Choose a method that's easy to understand and maintain, especially for complex codebases.
* Code reuse: Consider using the same iteration method throughout your project to ensure consistency.

**Library and Special Features**

In this benchmark, no special libraries or features are used. The focus is on comparing different iteration methods native to JavaScript.

If you'd like more information about other JavaScript iterations, such as `forEach` or `for...of`, let me know!

Related benchmarks:

for-in-hasOwnProperty vs object.keys-direct (version: 0)

Comparing performance of: for-in-hasOwnProperty vs Object.keys-direct vs Object.keys vs for-in

Created: 4 years ago by: Guest

Jump to the latest result

for-in-hasOwnProperty

Object.keys-direct

Object.keys

for-in

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):