Benchmark: JS Map foreach vs for of

Script Preparation code:

var testMap = new Map();
for(let i=0; i<1000; i++) {
 	testMap.set(`key${i}`,`value${i}`);                    
}

Tests:

foreach
testMap.forEach((v,k)=>{ `key: ${k}, value: ${v}` })
for... of
for(let [k,v] of testMap) { `key: ${k}, value: ${v}` }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for... of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
foreach	70802.3 Ops/sec
for... of	72288.9 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark definition consists of two test cases: `foreach` and `for...of`. Both test cases are designed to measure the performance of iterating over a Map object using different approaches.

**Script Preparation Code**

The script preparation code creates a new Map called `testMap` with 1000 key-value pairs, where each key is a string in the format `"keyX"` and each value is a string in the format `"valueX"`, where X is an integer ranging from 0 to 999.

**Html Preparation Code**

The html preparation code is empty, which means that the benchmarking process only focuses on the JavaScript execution time, without considering any UI-related factors.

**Test Cases**

There are two test cases:

1. **foreach**: This test case uses the `forEach` method to iterate over the Map object. The callback function takes two arguments: the value (`v`) and the key (`k`). The test code prints the key and value to the console using template literals.
2. **for...of**: This test case uses a `for...of` loop to iterate over the Map object's entries. The syntax is similar to traditional `for` loops, but instead of looping over indices, it directly iterates over the key-value pairs.

**Library and Purpose**

In both test cases, the library used is JavaScript, which provides a built-in way to work with objects, including Maps.

**Special JS Feature or Syntax**

The use of template literals (`${}`) in the callback function is a modern JavaScript feature that allows for easier string interpolation. This syntax was introduced in ECMAScript 2015 (ES6).

**Pros and Cons**

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

1. **foreach**:
	* Pros: Simple, widely supported, and easy to understand.
	* Cons: May have performance implications due to the overhead of method calls and iteration.
2. **for...of**:
	* Pros: More efficient, as it avoids the overhead of method calls and iteration.
	* Cons: May require more manual memory management (e.g., keeping track of key-value pairs).

**Other Considerations**

When choosing between `foreach` and `for...of`, consider the specific requirements of your application:

* If you need to iterate over a large dataset and don't mind paying the overhead of method calls, `foreach` might be sufficient.
* If performance is critical, especially for large datasets or real-time applications, `for...of` might be a better choice.

**Alternatives**

Other alternatives to measure performance in JavaScript could include:

1. **Native benchmarking libraries**: Examples like WebKit's `bench` library or Google's `benchmark` library.
2. **JavaScript frameworks**: Some frameworks, like React or Angular, provide built-in benchmarking tools or libraries.
3. **Custom benchmarking scripts**: Writing custom script to measure performance using a framework like Node.js's `perf_hooks` module.

Please note that the choice of alternative will depend on your specific needs and requirements.

Related benchmarks:

JS Map foreach vs for of (version: 0)

Comparing performance of: foreach vs for... of

Created: one year ago by: Guest

Jump to the latest result

foreach

for... of

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):