Benchmark: Reduce vs Map+FromEntries vs for loop

Script Preparation code:

var data = Array.from(Array(10000).keys());

Tests:

reduce
Object.entries(data).reduce((acc, [k, v]) => { acc[k] = v.toString(); return acc; }, {});
map + fromEntries
Object.fromEntries(Object.entries(data).map(([k, v]) => ([k, v.toString()])));
for loop
const dataObject = Object.entries(data) const acc = {} for (let i = 0; i < dataObject.length; i++) { const [k, v] = dataObject[i]; acc[k] = v.toString() }

Historical Performance Data aggregated from 36 community runs

Desktop Results:

Chrome 31 runs

for loop

3K/s

reduce

3K/s

map + fromEntries

1K/s

Fastest: for loop (2.1x faster)

View exact numbers

✓ for loop: 2,861 ops/sec
• reduce: 2,568 ops/sec
• map + fromEntries: 1,364 ops/sec

Firefox 5 runs

for loop

2K/s

map + fromEntries

2K/s

reduce

2K/s

Fastest: for loop (1.3x faster)

View exact numbers

✓ for loop: 1,980 ops/sec
• map + fromEntries: 1,508 ops/sec
• reduce: 1,508 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
map + fromEntries
for loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:148.0) Gecko/20100101 Firefox/148.0

Browser/OS: Firefox 148 on Mac OS X 10.15

View result in a separate tab

for loop

4K/s

reduce

3K/s

map + fromEntries

3K/s

View exact numbers

Test name	Executions per second
✓ for loop	3,558 Ops/sec
reduce	3,345 Ops/sec
map + fromEntries	2,628 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark compares the performance of three approaches for iterating over an object and converting its values to strings: `reduce`, `map + fromEntries`, and a traditional `for loop`.

**Tested Options**

1. **Reduce**: Uses `Array.prototype.reduce()` method to iterate over the object's entries and accumulate the converted values.
2. **Map + FromEntries**: Utilizes `Array.prototype.map()` to convert each value to a string, followed by `Object.fromEntries()` to create an object from the array of key-value pairs.
3. **For Loop**: Manually iterates over the object's entries using a traditional `for` loop.

**Pros and Cons**

* **Reduce**:
	+ Pros: Compact code, easy to read.
	+ Cons: May be slower due to the overhead of recursive accumulation.
* **Map + FromEntries**:
	+ Pros: Clear and concise code, avoids recursion.
	+ Cons: Requires two additional function calls, which can introduce overhead.
* **For Loop**:
	+ Pros: Control over iteration flow, no additional function calls.
	+ Cons: More verbose code, requires manual index management.

**Library/Functionality**

The `map()` and `fromEntries()` functions are part of the ECMAScript standard and are supported by most modern browsers. However, `reduce()` is also a standard function, but it's worth noting that some older versions of Internet Explorer may not support it.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes used in this benchmark.

**Other Alternatives**

If you prefer a different approach, here are some alternatives:

* **Lodash's `reduceBy()`**: A utility function from the Lodash library that provides a more concise and readable way to reduce an object by a key.
* **Array.prototype.forEach() with map() and spread operator**: Another alternative approach using `forEach()` to iterate over the object, followed by `map()` to convert values and the spread operator (`...`) to create an object from the array.

Keep in mind that these alternatives may not be relevant for this specific benchmark, but they can provide additional options for similar use cases.

Reduce vs Map+FromEntries vs for loop (version: 0)

Comparing performance of: `reduce vs map + fromEntries vs for loop`

Created: 5 years ago by: Guest

Go to the latest result

reduce

map + fromEntries

for loop

Historical Performance Data aggregated from 36 community runs

Desktop Results:

Chrome 31 runs

Firefox 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Reduce vs Map+FromEntries vs for loop (version: 0)

Comparing performance of: reduce vs map + fromEntries vs for loop

Created: 5 years ago by: Guest

Go to the latest result

reduce

map + fromEntries

for loop

Historical Performance Data aggregated from 36 community runs

Desktop Results:

Chrome 31 runs

Firefox 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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Comparing performance of: `reduce vs map + fromEntries vs for loop`