Benchmark: reduce vs map + fromEntries vs reduce spread

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()])));
reduce spread
Object.entries(data).reduce((acc, [k, v]) => ({ ...acc, [k]: v.toString(), }), {});

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

reduce

3K/s

map + fromEntries

1K/s

reduce spread

107/s

Fastest: reduce (29.9x faster)

View exact numbers

✓ reduce: 3,185 ops/sec
• map + fromEntries: 1,275 ops/sec
• reduce spread: 107 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
reduce spread

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:138.0) Gecko/20100101 Firefox/138.0

Browser/OS: Firefox 138 on Ubuntu

View result in a separate tab

reduce

2K/s

map + fromEntries

2K/s

reduce spread

0/s

View exact numbers

Test name	Executions per second
✓ reduce	2,327 Ops/sec
map + fromEntries	2,104 Ops/sec
reduce spread	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 benchmark test and its components.

**What is tested on the provided JSON?**

The benchmark tests three different approaches to achieve the same result:

1. `Object.entries(data).reduce((acc, [k, v]) => {\r\n  acc[k] = v.toString();\r\n  return acc;\r\n}, {});`
2. `Object.fromEntries(Object.entries(data).map(([k, v]) => ([k, v.toString()]));)`
3. `Object.entries(data).reduce((acc, [k, v]) => ({\r\n  ...acc,\r\n  [k]: v.toString(),\r\n}), {});`

These approaches aim to create a new object by iterating over the key-value pairs of an existing object (`data`) and converting each value to a string.

**Options compared:**

The three options are being compared:

* `reduce`: A method that iterates over an array (or other iterable) and applies a callback function to each element. The accumulator is updated with each iteration.
* `map + fromEntries`: This approach uses the `map` method to transform each value in `data` into a new array of key-value pairs, which is then passed to `Object.fromEntries`.
* `reduce spread`: A variation of the `reduce` method that spreads the accumulator (`acc`) as an object, allowing for more flexibility when assigning values.

**Pros and cons:**

Here's a brief summary of each approach:

* **Reduce**:
	+ Pros: Efficient use of memory, easy to implement.
	+ Cons: Can be slow if not implemented correctly, may not work well with large datasets.
* **Map + fromEntries**:
	+ Pros: Fast and efficient, works well with large datasets.
	+ Cons: May consume more memory due to the creation of an intermediate array, less intuitive than `reduce`.
* **Reduce spread**:
	+ Pros: Offers flexibility in assigning values to the accumulator, can be more readable.
	+ Cons: May not work as expected if the callback function is complex, may require additional considerations for edge cases.

**Library and purpose:**

There are no libraries mentioned in this benchmark. However, `Object.entries()` and `Object.fromEntries()` are part of the ECMAScript standard (ES6+) and are built-in methods for working with objects in JavaScript.

**Special JS feature or syntax:**

The use of spread syntax (`...`) is a modern JavaScript feature introduced in ES6+. It allows for the expansion of an object's properties into individual key-value pairs, making it easier to merge objects or create new objects from existing ones.

reduce vs map + fromEntries vs reduce spread (version: 0) Benchmark.js

Comparing performance of: `reduce vs map + fromEntries vs reduce spread`

Created: 6 years ago by: Guest

Go to the latest result

reduce

map + fromEntries

reduce spread

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 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 reduce spread (version: 0) Benchmark.js

Comparing performance of: reduce vs map + fromEntries vs reduce spread

Created: 6 years ago by: Guest

Go to the latest result

reduce

map + fromEntries

reduce spread

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 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 reduce spread`