Benchmark: For in vs Object.*.forEach vs Object.values 2

Script Preparation code:

var obj = new Object()
var keys = (new Array(10000)).fill(0).map((x, i) => { return i + 1 })
keys.forEach((x) => { obj['prop' + x] = x })

Tests:

For In
const arr = []; for (const key in obj) { arr.push(obj[key]); }
Object values
const arr = Object.values(obj);
Object keys for of
const arr = []; for (const key of Object.keys(obj)) { arr.push(obj[key]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For In
Object values
Object keys for of

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark is designed to compare three approaches for iterating over an object: `for-in`, `Object.values()`, and `Object.keys()` with the `for...of` loop. The goal is to determine which approach provides the best performance in JavaScript.

**Options Compared**

1. **For-In**: This traditional method uses the `in` operator to iterate over the object's own enumerable properties. It can also include inherited properties, which may impact performance.
2. **Object.values()**: This method returns an array of the object's own property values without including inherited properties. It is a more modern and efficient approach.
3. **Object.keys()` with `for...of` loop**: This method uses the `Object.keys()` function to get an array of the object's own enumerable property names, and then iterates over this array using a `for...of` loop.

**Pros and Cons of Each Approach**

1. **For-In**:
	* Pros: Wide browser support, easy to understand.
	* Cons: May include inherited properties, can be slower due to the need to check for property existence.
2. **Object.values()**:
	* Pros: Efficient, modern approach that doesn't include inherited properties.
	* Cons: Requires ES6+ compatibility, may not work in older browsers.
3. **Object.keys()` with `for...of` loop**:
	* Pros: Similar to `Object.values()`, but allows for more control over property iteration.
	* Cons: May require more browser support due to the use of `Object.keys()`.

**Library and Special JS Features**

None are mentioned in the provided benchmark.

**Other Considerations**

When choosing an approach, consider the following factors:

* Browser support: If you need to support older browsers, `for-in` might be a better choice.
* Performance: `Object.values()` is generally faster due to its optimized implementation.
* Code readability and maintainability: `for...of` loop can make code more concise and readable.

**Alternatives**

Other approaches for iterating over objects include:

1. **Using `Array.prototype.forEach()`**: This method is similar to `for-in`, but uses an array-based iteration instead of a property-based approach.
2. **Using `Object.getOwnPropertyNames()`**: This method returns an array of all properties (including inherited) on the object, and can be used with `forEach()` or other iteration methods.

In summary, the benchmark provides a comprehensive comparison of three approaches for iterating over objects in JavaScript, highlighting their pros and cons, and providing guidance on choosing the best approach based on specific requirements.

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:127.0) Gecko/20100101 Firefox/127.0

Browser/OS: Firefox 127 on Ubuntu

View result in a separate tab

Test name	Executions per second
For In	2418.2 Ops/sec
Object values	12333.5 Ops/sec
Object keys for of	1434.5 Ops/sec

Related benchmarks:

For in vs Object.*.forEach vs Object.values 2 (version: 0)

Comparing performance of: For In vs Object values vs Object keys for of

Created: 4 months ago by: Guest

Jump to the latest result

For In

Object values

Object keys for of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):