Benchmark: Creating partial objects (Array.reduce vs for loop)

Script Preparation code:

var keys = ['foo', 'baz']
var obj = {
    foo: 195,
    bar: 'testing',
    baz: 'more testing',
    qux: true
}

Tests:

Array.reduce
const partial = keys.reduce((acc, cur) => Object.assign(acc, { [cur]: obj[cur] }), {})
for loop
const partial = {} for (const key of keys) partial[key] = obj[key]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.reduce
for loop

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Overview**

The benchmark compares two approaches for creating partial objects: using `Array.reduce()` versus using a traditional `for` loop. The test creates an object with some keys (`foo`, `baz`) and their corresponding values, and then attempts to create a new object that only includes these specific properties.

**Approach 1: Array.reduce()**

The first approach uses `Array.reduce()` to iterate over the array of keys (`keys`) and create a new object by merging the properties of the original object (`obj`). The `reduce()` method applies a callback function to each element in the array, accumulating a result. In this case, the callback function `Object.assign(acc, { [cur]: obj[cur] })` merges the current property into the accumulator (`acc`) and returns the new merged object.

Pros:

* Concise and expressive code
* Easy to read and maintain
* Optimized for performance

Cons:

* Limited control over the iteration process
* May have performance issues if the array is very large or the callback function is complex

**Approach 2: Traditional for loop**

The second approach uses a traditional `for` loop to iterate over the array of keys (`keys`) and create a new object by assigning properties manually. The loop iterates over each key, creates a property with the corresponding value from the original object (`obj[key]`), and assigns it to the partial object.

Pros:

* More control over the iteration process
* Can be more flexible for complex logic or edge cases

Cons:

* More verbose and less readable than `Array.reduce()`
* May have performance issues if the array is very large or the loop is complex

**Library/Functionality**

In this benchmark, no libraries are used beyond the standard JavaScript features. However, it's worth noting that `Object.assign()` is a part of the ECMAScript specification and is widely supported across modern browsers.

**Special JS Feature/Syntax**

No special JavaScript features or syntax are mentioned in the benchmark definition or test cases.

**Other Alternatives**

If you're interested in exploring alternative approaches to creating partial objects, here are some other options:

1. `Object.create()`: Similar to `Array.reduce()`, but uses the prototype chain instead of an array.
2. `for...in` loop: Iterates over the properties of the original object using its own syntax.
3. `map()` and `reduce()` together: Can be used to create a partial object by mapping over the array of keys and reducing it into a single object.
4. Object literal with spread syntax (`{ ... }`: Creates an object from an existing object by spreading its properties onto a new object.

Keep in mind that each approach has its own trade-offs, and the best choice will depend on the specific use case and requirements.

Related benchmarks:

Creating partial objects (Array.reduce vs for loop) (version: 0)

Comparing performance of: Array.reduce vs for loop

Created: 3 years ago by: Guest

Jump to the latest result

Array.reduce

for loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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