Benchmark: Object.entries VS Object.keys VS Object.keys with extra array

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
const newObj = {}; Object.keys(window.parentObj).forEach((k, i) => { if ((i % 2) === 0) { newObj[k] = window.parentObj[k]; } });
Object.keys with extra array
const newObj = {}; Object.keys(window.parentObj).forEach((k, i) => { const [extraK, v] = [k, window.parentObj[k]] if ((i % 2) === 0) { newObj[extraK] = v; } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.entries
Object.keys
Object.keys with extra array

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark test case on MeasureThat.net, which compares the performance of three approaches for iterating over an object's keys:

1. `Object.entries()`
2. `Object.keys()`
3. `Object.keys()` with an additional array to extract both key and value.

**Options Compared**

The benchmark tests the following options:

* `Object.entries()`: Returns an array of a given object's own enumerable string-keyed property [key, value] pairs.
* `Object.keys()`: Returns an array of all the available keys for that object.
* `Object.keys()` with extra array: This approach is similar to `Object.keys()`, but it also extracts the corresponding values using an additional array.

**Pros and Cons**

Here's a brief summary of each option:

### Object.entries()

* Pros:
	+ Returns both key and value in a single iteration, which can be more efficient for large objects.
	+ Can be used to directly assign values to new objects without iterating over the keys separately.
* Cons:
	+ Requires 2 iterations (first to get keys, second to iterate over entries).
	+ May have slower performance due to additional iteration.

### Object.keys()

* Pros:
	+ Faster than `Object.entries()` since it only iterates over keys once.
	+ More straightforward and easier to understand for those familiar with the method.
* Cons:
	+ Returns only the keys, requiring an additional step to iterate over values.
	+ May not be as efficient if the object has a large number of keys.

### Object.keys() with extra array

* Pros:
	+ Combines the benefits of both approaches by extracting key and value in a single iteration.
	+ Can potentially improve performance since it avoids the need for additional iterations.
* Cons:
	+ Requires more complex logic to extract values, which can increase readability issues if not done correctly.

**Library Usage**

None of the benchmarked options use external libraries. The `window.parentObj` variable is used as a mock object, and the `makeid()` function is a custom utility for generating random IDs.

**Special JS Features/Syntax**

There are no special JavaScript features or syntaxes used in this benchmark.

**Alternative Approaches**

Other approaches to iterate over an object's keys might include:

* Using a `for...in` loop
* Utilizing a library like Lodash or Underscore.js for iteration and manipulation of objects
* Implementing a custom iterator function using the `Symbol.iterator` method

However, these alternatives are not tested in this specific benchmark.

Related benchmarks:

Object.entries VS Object.keys VS Object.keys with extra array (version: 0)

Comparing performance of: Object.entries vs Object.keys vs Object.keys with extra array

Created: 7 years ago by: Guest

Jump to the latest result

Object.entries

Object.keys

Object.keys with extra array

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):