Benchmark: map iteration - MeasureThat.net

Script Preparation code:

var obj = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6,
  g: 7,
  h: 8,
  i: 9,
  j: 10,
  k: 11,
  l: 12,
  m: 13,
  n: 14,
  o: 15,
  p: 16,
  q: 17,
  r: 18,
  s: 19,
  t: 20,
  u: 21,
  v: 22,
  w: 23,
  x: 24,
  y: 25,
  z: 26
};
var map = new Map(Object.entries(obj));

Tests:

entries()
let total = 0; for (const [key, value] of map) { total += value; }
for of
let total = 0; for (const [key, value] of map.entries()) { total += value; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
entries()
for of

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:145.0) Gecko/20100101 Firefox/145.0

Browser/OS: Firefox 145 on Mac OS X 10.15

View result in a separate tab

entries()

1.4M/s

for of

1.4M/s

View exact numbers

Test name	Executions per second
✓ entries()	1,430,810 Ops/sec
for of	1,427,501 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's being tested, compared, and their pros and cons.

**Benchmark Definition**

The test case is designed to measure the performance difference between using `map.entries()` and `for...of` loop with the `Map` data structure in JavaScript. The script preparation code creates a large object (`obj`) and converts it into a `Map`, named `map`.

**Comparison Options:**

1. **Entries()**: Uses the `map.entries()` method to iterate over the map's key-value pairs.
2. **For...of Loop**: Uses a traditional `for...of` loop with a custom iterator function that yields the key-value pairs of the map.

**Pros and Cons of Each Approach:**

* **Entries():**
	+ Pros:
		- More concise and expressive code
		- Easier to read and maintain, especially for those familiar with functional programming concepts.
	+ Cons:
		- May incur additional overhead due to method call and argument passing.
		- Can lead to slower performance if the map is very large or has a complex structure (due to string interning and object property lookup).
* **For...of Loop:**
	+ Pros:
		- Can be more efficient for very large maps, as it avoids the overhead of method calls and can utilize optimized array iteration algorithms.
	+ Cons:
		- Requires more code and is less concise than `entries()`.
		- May require additional bookkeeping to handle edge cases like empty maps or key-value pairs.

**Library and Purpose:**

There is no explicit library mentioned in the benchmark definition. However, JavaScript's built-in `Map` data structure is used, which provides a simple way to store and iterate over key-value pairs.

**Special JS Feature/Syntax:**

* The `for...of` loop with a custom iterator function is an example of using iterators in JavaScript. An iterator is a special type of object that allows iteration over a sequence (like a map or array). In this case, the custom iterator function simply yields the key-value pairs of the map.

**Other Considerations:**

* The benchmark measures the performance difference between these two approaches on a single test case, which may not be representative of real-world scenarios.
* Other factors like memory allocation, garbage collection, and cache efficiency might also impact performance in this benchmark.
* The use of a Chrome browser with specific hardware and OS configuration can introduce additional variability.

**Alternatives:**

Other alternatives for iterating over maps or arrays in JavaScript include:

* Using `forEach()` method (which is generally slower than `for...of` loop)
* Implementing a custom iterator function using a recursive approach
* Utilizing specialized libraries like Lodash or Ramda, which provide optimized iteration algorithms.

However, the choice of iteration method ultimately depends on the specific requirements and constraints of your project.

map iteration (version: 0)

Comparing performance of: `entries() vs for of`

Created: 4 years ago by: Guest

Go to the latest result

entries()

for of

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

map iteration (version: 0)

Comparing performance of: entries() vs for of

Created: 4 years ago by: Guest

Go to the latest result

entries()

for of

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `entries() vs for of`