Benchmark: Object.entries VS Object.keys VS Object.entries with for of

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 + foreach
const newObj = {}; Object.keys(window.parentObj).forEach((k) => { newObj[k] = window.parentObj[k]; });
Object.keys + foreach
const newObj = {}; Object.entries(window.parentObj).forEach(([k, v]) => { newObj[k] = v; });
Object.entries + for of
const newObj = {}; for (const [k, v] of Object.entries(window.parentObj)) { newObj[k] = v; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.entries + foreach
Object.keys + foreach
Object.entries + for of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:89.0) Gecko/20100101 Firefox/89.0

Browser/OS: Firefox 89 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Object.entries + foreach	32480.1 Ops/sec
Object.keys + foreach	65823.9 Ops/sec
Object.entries + for of	62719.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

I'll break down the benchmark and its test cases for you.

**Benchmark Definition**

The benchmark is designed to compare the performance of three different ways to iterate over an object in JavaScript:

1. `Object.keys()` with `forEach`
2. `Object.entries()` with `forEach`
3. `Object.entries()` with `for...of`

The script preparation code creates a large object (`window.parentObj`) with 100 properties, each generated by a random string.

**Options Compared**

Here's what's being compared:

* `Object.keys()` + `forEach`: Iterates over the object's keys using `Object.keys()`, which returns an array of strings. The `forEach` method is then used to iterate over this array.
* `Object.entries()` + `forEach`: Iterates over the object's key-value pairs using `Object.entries()`, which returns an array of arrays containing the key and value. The `forEach` method is then used to iterate over this array.
* `Object.entries()` + `for...of`: Similar to the previous case, but uses a `for...of` loop to iterate over the object's key-value pairs.

**Pros and Cons**

Here are some pros and cons of each approach:

* `Object.keys() + forEach`:
	+ Pros: Simple and easy to read. Works well for objects with only string keys.
	+ Cons: Can be slower than other methods, especially for large objects, since it requires iterating over an array.
* `Object.entries() + forEach`:
	+ Pros: More efficient than `Object.keys() + forEach`, especially for large objects, since it avoids creating an array.
	+ Cons: Requires modern JavaScript features (ECMAScript 2015 and later) to work with the spread operator (`[...array]`) used in the benchmark.
* `Object.entries() + for...of`:
	+ Pros: Similar performance to `Object.entries() + forEach`, but more concise and readable.
	+ Cons: Requires modern JavaScript features (ECMAScript 2015 and later) to work with the spread operator (`[...array]`) used in the benchmark.

**Libraries Used**

None.

**Special JS Features/Syntax**

The benchmark uses several modern JavaScript features:

* ES6 spread operator (`[...]`)
* `for...of` loop
* Modern JavaScript syntax (e.g., template literals, arrow functions)

These features are not supported in older versions of JavaScript and require at least ECMAScript 2015 to work.

**Alternatives**

Other alternatives for iterating over objects include:

* Using a traditional `for` loop: `for (var key in obj) { ... }`
* Using a library like Lodash, which provides a `keys()` method for iterating over object keys.
* Using a data structure like an array or a Map to store the object's values.

Related benchmarks:

Object.entries VS Object.keys VS Object.entries with for of (version: 0)

Comparing performance of: Object.entries + foreach vs Object.keys + foreach vs Object.entries + for of

Created: 3 years ago by: Guest

Jump to the latest result

Object.entries + foreach

Object.keys + foreach

Object.entries + for of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):