Benchmark: For in vs Object.*.forEach vs Object.values

Script Preparation code:

var obj = new Object()
var keys = (new Array(10000)).fill(0).map((x, i) => { return i + 1 })
keys.forEach((x) => { obj['prop' + x] = x })

Tests:

For In
for (var key in obj) { console.log(obj[key]); }
Object values
for(let value of Object.values(obj)){ console.log(value); }
Object keys forEach
Object.keys(obj).forEach(key => console.log(obj[key]));
Object entries forEach
Object.entries(obj).forEach(([key, value]) => console.log(key,'->',value));
object values forEach
Object.values(obj).forEach(value => console.log(value));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For In
Object values
Object keys forEach
Object entries forEach
object values forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser/OS: Chrome 137 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
For In	53.2 Ops/sec
Object values	50.3 Ops/sec
Object keys forEach	49.6 Ops/sec
Object entries forEach	34.7 Ops/sec
object values forEach	22.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Overview**

The benchmark being tested is a comparison of four different ways to iterate over an object in JavaScript: `for` loop, `Object.values()`, `Object.keys().forEach()`, and `Object.entries().forEach()`.

**Test Cases**

Each test case represents a specific iteration method:

1. **For In**: Iterates over the object's properties using a traditional `for` loop.
2. **Object values**: Uses the `Object.values()` method to get an array of the object's property values.
3. **Object keys forEach**: Uses the `Object.keys()` method and the `forEach()` method to iterate over the object's property keys.
4. **Object entries forEach**: Uses the `Object.entries()` method and the `forEach()` method to iterate over the object's key-value pairs.

**Library: None**

None of the test cases use any external libraries, making them self-contained and easily reproducible.

**Special JavaScript Features/Syntax**

* None of the test cases rely on special JavaScript features or syntax that would affect their performance. They focus on the iteration methods themselves.

**Pros and Cons of Each Approach**

1. **For In**:
	* Pros: Simple, intuitive, and well-supported by most browsers.
	* Cons: Can be slower due to the use of `for` loops and potentially more memory usage.
2. **Object values**:
	* Pros: Fast and efficient, as it creates an array of property values in a single step.
	* Cons: May not work as expected if the object is very large or has many properties, as it can lead to performance issues due to memory allocation.
3. **Object keys forEach**:
	* Pros: Can be faster than traditional `for` loops and creates an array of property keys in a single step.
	* Cons: May not work as expected if the object is very large or has many properties, as it can lead to performance issues due to memory allocation.
4. **Object entries forEach**:
	* Pros: Provides both key and value access, making it more convenient than traditional iteration methods.
	* Cons: Can be slower than using `Object.values()` or `Object.keys().forEach()`, as it requires creating an array of key-value pairs.

**Other Alternatives**

If you need to iterate over an object in JavaScript, other alternatives include:

* Using `Array.prototype.forEach()` with a custom callback function.
* Using the `map()` method to create a new array of values.
* Using a library like Lodash or Ramda for functional programming-style iteration.

In conclusion, each test case represents a different approach to iterating over an object in JavaScript. While there is no clear winner in terms of performance, `Object.values()` and `Object.keys().forEach()` tend to be faster and more efficient. The choice of method ultimately depends on the specific requirements and constraints of your use case.

Related benchmarks:

For in vs Object.*.forEach vs Object.values (version: 0)

Comparing performance of: For In vs Object values vs Object keys forEach vs Object entries forEach vs object values forEach

Created: 5 years ago by: Guest

Jump to the latest result

For In

Object values

Object keys forEach

Object entries forEach

object values forEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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