Benchmark: Iterate Map entries

Script Preparation code:

var map = new Map();
for (var i = 0; i < 10000; i++) {
	map[Math.random()] = Math.random();
}

Tests:

For Entries
for (var [key, value] of map.entries()) { key value }
Foreach
map.forEach(function(value, key) { key value }, map)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For Entries
Foreach

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
For Entries	64019900.0 Ops/sec
Foreach	43921876.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark defines two test cases:

1. **Iterate Map entries**: This test case creates an empty `Map` object and populates it with 10,000 key-value pairs using the `Math.random()` function to generate random keys.
2. **For Entries** (Test Case): This is a specific implementation of iterating over the map's entries. It uses the `for...of` loop syntax, which was introduced in ECMAScript 2017 (ES7). The test case iterates over the map's entries and logs each key and value.
3. **Foreach** (Test Case): This is another implementation of iterating over the map's entries using the traditional `forEach()` method with a callback function.

**Options Compared**

The benchmark compares the performance of two approaches:

1. Using the `for...of` loop syntax to iterate over the map's entries.
2. Using the traditional `forEach()` method with a callback function.

**Pros and Cons**

* **For Entries (ES7)**:
	+ Pros: More concise and expressive code, can be faster due to optimized compiler output.
	+ Cons: Requires support for ES7 syntax, may not work in older browsers or environments.
* **Foreach (Traditional)**:
	+ Pros: Widely supported across different browsers and environments, no need for special syntax.
	+ Cons: Less concise and expressive code, may be slower due to the callback function overhead.

**Library**

The `Map` object is a built-in JavaScript data structure that stores key-value pairs. It was introduced in ECMAScript 2015 (ES6) as part of the standard library.

**Special JS Feature/Syntax**

No special syntax or features are used in this benchmark, making it accessible to a wide range of developers and environments.

**Other Considerations**

When writing microbenchmarks like this one, consider the following:

* Keep the test cases simple and focused on a specific piece of functionality.
* Use a consistent setup and preparation code for all test cases.
* Choose a suitable benchmarking framework or tool (in this case, MeasureThat.net).
* Run multiple iterations to ensure reliable results.
* Consider additional factors like system load, network latency, and cache effects that may impact performance.

**Alternatives**

If you wanted to write similar benchmarks using different approaches, consider the following alternatives:

1. Using `Array.prototype.forEach()` instead of the traditional `forEach()` method with a callback function.
2. Implementing your own iterator or iterator-like object for the map entries.
3. Comparing the performance of other JavaScript data structures, such as `Set` or arrays, when used for iteration.
4. Investigating the impact of various optimization techniques, like caching or memoization, on the benchmarked code.

Keep in mind that each alternative will introduce new variables and complexities to consider when writing a benchmark.

Related benchmarks:

Iterate Map entries (version: 0)

Comparing performance of: For Entries vs Foreach

Created: 6 years ago by: Guest

Jump to the latest result

For Entries

Foreach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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