Benchmark: Object.values vs for in loop v2

Tests:

mapForIn
const obj = { "1": { id: 1 }, "2": { id: 2 }, "3": { id: 3 }, "4": { id: 4 }, "5": { id: 5 }, "6": { id: 6 }, "7": { id: 7 }, "8": { id: 8 }, "9": { id: 9 }, "10": { id: 10 }, "11": { id: 11 }, "12": { id: 12 }, "13": { id: 13 }, "14": { id: 14 }, "15": { id: 15 }, "16": { id: 16 }, "17": { id: 17 }, "18": { id: 18 }, "19": { id: 19 }, "20": { id: 20 } }; const mapForIn = (func) => { const arr = []; for (let key in obj) { if (Object.hasOwnProperty(obj)) { arr.push(func(obj[key], arr.length - 1)); } } return arr; } mapForIn((item, index) => item);
mapValues
const obj = { "1": { id: 1 }, "2": { id: 2 }, "3": { id: 3 }, "4": { id: 4 }, "5": { id: 5 }, "6": { id: 6 }, "7": { id: 7 }, "8": { id: 8 }, "9": { id: 9 }, "10": { id: 10 }, "11": { id: 11 }, "12": { id: 12 }, "13": { id: 13 }, "14": { id: 14 }, "15": { id: 15 }, "16": { id: 16 }, "17": { id: 17 }, "18": { id: 18 }, "19": { id: 19 }, "20": { id: 20 } }; const mapValues = (func) => Object.values(obj).map(func); mapValues((item, index) => item);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
mapForIn
mapValues

Fastest: N/A

Slowest: N/A

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

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Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The provided benchmark compares two approaches to iterate over an object: `Object.values` and a custom implementation using a `for...in` loop (`mapForIn`) or array methods (`mapValues`). The goal is to determine which approach is faster on JavaScript engines, specifically on Chrome 70 running on Linux.

**Options Compared**

1. **Object.values**: This method returns an array of the object's values.
2. **mapForIn**: A custom implementation using a `for...in` loop that iterates over the object's keys and calls a provided function for each value.
3. **mapValues**: Another custom implementation using `Object.values` to get an array of values, which is then mapped over with a provided function.

**Pros and Cons**

1. **Object.values**:
	* Pros: Simple and efficient way to get object values as an array.
	* Cons: May not be the fastest approach since it requires creating an intermediate array.
2. **mapForIn**:
	* Pros: Can provide more control over iteration, especially when working with complex objects or custom data structures.
	* Cons: May be slower due to the use of a `for...in` loop and additional function calls.
3. **mapValues**:
	* Pros: Combines the efficiency of `Object.values` with the flexibility of array methods like `map`.
	* Cons: Requires two function calls, which may add overhead.

**Library Used**

In this benchmark, `Array.prototype.map()` is used in both `mapForIn` and `mapValues`. This library provides a convenient way to perform operations on arrays, but it also incurs some overhead due to the creation of intermediate objects.

**Special JS Feature/Syntax**

The `for...in` loop in `mapForIn` uses the `Object.hasOwnProperty()` method to check if the current iteration is a property of the object. This is not a special feature per se, but rather an optimization used by some JavaScript engines to avoid iterating over inherited properties.

**Other Alternatives**

If you're looking for alternative approaches to iterate over objects in JavaScript, consider the following:

* **for...of**: A newer `for` loop syntax that can be used to iterate over arrays and objects using a simple loop.
* **Array.prototype.forEach()`: Similar to `map()`, but without the return value.
* **Object.keys()`**: Returns an array of object keys, which can then be iterated over using a loop.

Keep in mind that these alternatives may have different trade-offs in terms of performance, control, and code readability.

Related benchmarks:

Object.values vs for in loop v2 (version: 0)

Comparing performance of: mapForIn vs mapValues

Created: 6 years ago by: Guest

Jump to the latest result

mapForIn

mapValues

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):