Benchmark: Object.entries VS Object.keys.map

Script Preparation code:

function makeid() {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (var i = 0; i < 5; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));

  return text;
}

window.parentObj = {};

for (let i = 0; i < 100; i++) {
	window.parentObj[makeid()] = makeid();
}

Tests:

Object.entries
const newObj = {}; Object.entries(window.parentObj).forEach(([k, v], i) => { if ((i % 2) === 0) { newObj[k] = v; } });
Object.keys.map
const newObj = {}; Object.keys(window.parentObj).map(key => [key, window.parentObj[key]]).forEach(([k, v], i) => { if ((i % 2) === 0) { newObj[k] = v; } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.entries
Object.keys.map

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark for you.

**What is being tested?**

The benchmark is comparing two approaches to iterate over an object's key-value pairs: `Object.entries` and `Object.keys`.map`.

**Options compared:**

1. **Object.entries**: This method returns an array of a given object's own enumerable string keyed property [key, value] pairs.
2. **Object.keys().map**: This approach uses the `Object.keys()` method to get an array of an object's own enumerable property names, and then uses the `map` function to transform each key into an array of [key, value] pairs.

**Pros and Cons:**

* **Object.entries**:
	+ Pros:
		- More concise and expressive syntax.
		- Returns both keys and values in a single array, making it easier to process them together.
	+ Cons:
		- May be slower for very large objects, as `Object.keys()` can return an array of all property names, even if they are not used.
* **Object.keys().map**:
	+ Pros:
		- Can be faster for very large objects, as it only returns the keys and allows for more control over processing them.
	+ Cons:
		- Requires using a map function to transform each key into an array of [key, value] pairs, which can add overhead.

**Library usage:**

In this benchmark, no external libraries are explicitly mentioned. However, `window.parentObj` is used as an object, suggesting that the benchmark is running in a browser environment where `parent` and `child` windows can be referenced through `window.parent`.

**Special JS feature or syntax:**

None are explicitly mentioned.

**Benchmark preparation code:**

The script preparation code generates a random string (`makeid()`) and assigns it as a key to an object, repeated 100 times. This creates a large object with many properties, which is used for the benchmark.

**Alternative approaches:**

Other ways to iterate over an object's key-value pairs could include:

* Using `for...in` loop
* Using `Object.getOwnPropertyNames()` and then processing each property name individually
* Using a library like Lodash or Ramda to perform the iteration

Note that these alternatives may have different performance characteristics and trade-offs compared to `Object.entries` and `Object.keys().map`.

Related benchmarks:

Object.entries VS Object.keys.map (version: 1)

Comparing performance of: Object.entries vs Object.keys.map

Created: 4 years ago by: Registered User

Jump to the latest result

Object.entries

Object.keys.map

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):