Benchmark: for-in vs object.keys to array 2

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in
for (var i=10000; i > 0; i--) { const test = [] for (var key in obj) { test.push({key, value: obj[key]}); } }
Object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj).map(key => ({key, value: obj[key]})); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Object.keys

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.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to compare two approaches for iterating over an object in JavaScript:

1. `for-in` loop
2. Using `Object.keys()` and `map()`

The benchmark creates a sample object with 10 properties, all initialized to the value 1.

**Options Being Compared**

There are two options being compared:

* **Option 1: `for-in` loop**
	+ The `for-in` loop iterates over the object's property names (keys) in iteration order. In this case, it will iterate over the keys in alphabetical order.
	+ This approach has some advantages:
		- It can be more straightforward to implement, as it doesn't require knowledge of the object's structure or properties.
	+ However, it also has some disadvantages:
		- It can be slower due to the overhead of iterating over property names, which may not be present in all browsers.
		- It can also lead to unexpected behavior if the object's properties are modified during iteration (e.g., adding or removing properties).
* **Option 2: Using `Object.keys()` and `map()`**
	+ This approach uses the `Object.keys()` method to get an array of property names, which is then piped into the `map()` function.
	+ This approach has some advantages:
		- It's generally faster than the `for-in` loop, as it avoids the overhead of iterating over property names.
	+ However, it also has some disadvantages:
		- It requires knowledge of the object's structure and properties to implement correctly.
		- If the object's properties are modified during iteration (e.g., adding or removing properties), it can lead to unexpected behavior.

**Library Used**

There is no explicit library mentioned in the benchmark definition. However, the `Object.keys()` method is a part of the ECMAScript standard and is implemented by most modern JavaScript engines, including browsers like Firefox.

**Special JS Feature/Syntax**

The benchmark uses the following special feature:

* The `map()` function returns a new array with the results of applying the provided function to each element in the original array. In this case, it's used to transform each property name into an object with the key-value pair.

Overall, the benchmark is designed to provide insight into the performance differences between two approaches for iterating over objects in JavaScript. By comparing these two options, developers can choose the approach that best fits their needs and optimize their code accordingly.

**Other Alternatives**

Some other alternatives to consider when iterating over objects include:

* Using `for...in` with a `try-catch` block to handle any potential errors or unexpected behavior.
* Using `forEach()` instead of `map()`, which is often faster for small arrays but may have performance issues for large datasets.
* Using `Object.entries()` instead of `Object.keys()`, which returns an array of key-value pairs rather than just property names.

However, these alternatives are not explicitly tested in this benchmark and may have different trade-offs depending on the specific use case.

Related benchmarks:

for-in vs object.keys to array 2 (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 3 years ago by: Guest

Jump to the latest result

for-in

Object.keys

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):