Benchmark: Object reading JS - 2

HTML Preparation code:

<div id="show"></div>

Script Preparation code:

var obj = {}
var maxsize = 100

for (let i = 0; i < maxsize; i++) {
  obj[`i_${i}`] = i;
}

Tests:

for in
let total = 0; for (let k in obj) { const test = obj[k] + 1; total += test; }
for classic
let total = 0; const keys = Object.keys(obj) for (let i = 0; i < maxsize; i++) { const test = obj[keys[i]] + 1; total += test; }
for classic values
let total = 0; const values = Object.values(obj) for (let i = 0; i < maxsize; i++) { const test = values[i] + 1; total += test; }
for classic fixed keys
let total = 0; const keys = Object.keys(obj) for (let i = 0; i < maxsize; i++) { const test = obj[`i_${i}`] + 1; total += test; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for in
for classic
for classic values
for classic fixed keys

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Browser/OS: Chrome 105 on Windows

View result in a separate tab

Test name	Executions per second
for in	71252.4 Ops/sec
for classic	44487.0 Ops/sec
for classic values	39959.2 Ops/sec
for classic fixed keys	32582.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Benchmark Overview**

The benchmark is designed to compare the performance of different approaches for iterating over an object's properties in JavaScript. The object contains a large number of key-value pairs, and the goal is to measure which approach is fastest.

**Options Compared**

There are four options compared:

1. **"for in"`: This approach uses the `in` operator to iterate over the object's properties. It's a traditional way of iterating over an object's properties, but it can be slower due to the overhead of the `in` operator.
2. **"for classic"`: This approach uses the `Object.keys()` method to get an array of the object's property names, and then iterates over this array using a `for` loop. This approach is often faster than "for in" because it avoids the overhead of the `in` operator.
3. **"for classic values"`: This approach uses the `Object.values()` method to get an array of the object's property values, and then iterates over this array using a `for` loop. Similar to "for classic", this approach is faster than "for in".
4. **"for classic fixed keys"`: This approach uses template literals (`i_${i}`) to access specific properties of the object directly, without needing to use the `in` operator or `Object.keys()`/`Object.values()`. This approach is likely to be the fastest because it minimizes overhead.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* **"for in"`:
	+ Pros: simple and easy to understand
	+ Cons: can be slower due to `in` operator overhead
* **"for classic"`:
	+ Pros: often faster than "for in" due to reduced overhead
	+ Cons: requires using `Object.keys()` method, which may introduce additional overhead
* **"for classic values"`:
	+ Pros: similar to "for classic", but with an added benefit of iterating over property values instead of names
	+ Cons: still requires using `Object.values()` method, which may introduce additional overhead
* **"for classic fixed keys"`:
	+ Pros: likely to be the fastest due to minimal overhead
	+ Cons: requires template literals and direct property access, which can be less intuitive for some developers

**Other Considerations**

The benchmark is designed to measure performance under specific conditions (i.e., iterating over a large object with many properties). The results may not generalize well to other scenarios or edge cases.

It's worth noting that the `Object.keys()` and `Object.values()` methods are part of the ECMAScript standard, so they should be supported by most modern JavaScript engines. However, there may be variations in implementation across different browsers or environments.

**Library/Functions Used**

In this benchmark, the following libraries/functions are used:

* `Object.keys()`: returns an array of the object's property names
* `Object.values()`: returns an array of the object's property values
* Template literals (`i_${i}`): allow direct access to specific properties of the object

**Special JS Features/Syntax**

This benchmark uses template literals (e.g., `i_${i}`) to access specific properties of the object directly. This is a relatively modern JavaScript feature that allows for more concise and expressive code.

Other alternatives to these approaches might include:

* Using `for...of` loops, which are gaining popularity as a way to iterate over arrays and objects
* Utilizing built-in array methods like `forEach()` or `reduce()`, which can simplify certain types of iterations
* Leveraging library functions like `lodash.each()` or `ramda.forEach()` for more functional programming-style iterations

Keep in mind that these alternatives may not be suitable for all scenarios, and the choice ultimately depends on the specific requirements and constraints of your project.

Related benchmarks:

Object reading JS - 2 (version: 0)

Comparing performance of: for in vs for classic vs for classic values vs for classic fixed keys

Created: 2 years ago by: Guest

Jump to the latest result

for in

for classic

for classic values

for classic fixed keys

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):