Benchmark: for-in vs object.keys vs object.values for objects perf 5

Script Preparation code:

var obj =[...new Array(10000)].reduce((o,_,i)=>{
  	o[i+'-id']={id:i};
	return o;
},{});

Tests:

for-in
for (var key in obj) { console.log(obj[key].id); }
Object.keys
Object.keys(obj).forEach(key => console.log(obj[key].id));
Object.values
Object.values(obj).forEach(n => console.log(n.id));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Object.keys
Object.values

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.5845.713 YaBrowser/23.9.5.713 (corp) Yowser/2.5 Safari/537.36

Browser/OS: Yandex Browser 23 on Windows

View result in a separate tab

Test name	Executions per second
for-in	31.1 Ops/sec
Object.keys	34.3 Ops/sec
Object.values	34.2 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark, "for-in vs object.keys vs object.values for objects perf 5", compares the performance of three different approaches to iterate over an array of objects in JavaScript:

1. `for-in`
2. `Object.keys()`
3. `Object.values()` (introduced in ECMAScript 2019)

**Options Compared**

The benchmark tests the execution speed of each approach on a large dataset of 10,000 objects.

* `for-in`: uses a traditional for loop to iterate over the object's properties
* `Object.keys()`: returns an array of property names that can be iterated over using a foreach loop or other iteration methods
* `Object.values()`: returns an array of property values that can also be iterated over

**Pros and Cons**

Here are some pros and cons of each approach:

### for-in

Pros:

* Simple to implement and understand
* Works with both objects and arrays

Cons:

* Can iterate over inherited properties, which may not be desirable in all cases
* May have performance issues if the object has a large number of properties

### Object.keys()

Pros:

* Returns an array of property names only (not including inherited or computed properties)
* Can be more efficient than `for-in` because it avoids iterating over unnecessary properties

Cons:

* Requires additional code to iterate over the returned array
* May have performance issues if the object is very large

### Object.values()

Pros:

* Returns an array of property values only (not including keys or computed properties)
* Can be more efficient than `Object.keys()` because it avoids iterating over unnecessary arrays
* Introduced in ECMAScript 2019, making it a modern and optimized choice

Cons:

* May have performance issues if the object is very large due to the overhead of creating an array
* Requires additional code to iterate over the returned array

**Library Usage**

None.

**Special JS Features or Syntax**

None mentioned.

**Alternative Approaches**

Other approaches to iterate over objects in JavaScript include:

1. Using `Array.prototype.forEach()` with a callback function
2. Using `for...of` loops (introduced in ECMAScript 2015)
3. Using libraries like Lodash's `_.forEachObject()` or underscore.js's `_each()`

However, the benchmark is primarily focused on comparing the performance of `Object.keys()` and `Object.values()` with traditional for loops (`for-in`) and foreach loops (`Array.prototype.forEach()`), making these alternatives less relevant to this specific comparison.

Related benchmarks:

for-in vs object.keys vs object.values for objects perf 5 (version: 1)

Comparing performance of: for-in vs Object.keys vs Object.values

Created: one year ago by: Registered User

Jump to the latest result

for-in

Object.keys

Object.values

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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