Benchmark: Filter vs reduce objects test 12312412412

Script Preparation code:

var arr = [];
for (var i = 0; i < 12345; i++) {
  arr[i] = {
    name: "test-name" + i,
  	id: i,
    value: i,
    metadata: {
      position: i
    },
  };
}

function someFn(i) {
  return i.metadata.position % 2 === 0;
}

var sumReduce = 0,
  sumFilter = 0;

Tests:

reduce
sumReduce = arr.reduce((prevValue, item) => someFn(item) ? ++prevValue : prevValue, 0);
filter
sumFilter = arr.filter(elem => someFn(elem)).length

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
filter

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 dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The benchmark is designed to compare two approaches for filtering and summing an array of objects in JavaScript: `reduce` and `filter`. The script preparation code creates an array of 12,345 objects with a fixed structure, each containing `name`, `tid`, `value`, and `metadata` properties. A custom function `someFn` is defined to filter the array based on the `position` property.

**Options Compared**

Two options are compared:

1. **Reduce**: Uses the `Array.prototype.reduce()` method to sum up only the elements for which `someFn` returns `true`.
2. **Filter**: Uses the `Array.prototype.filter()` method to create a new array containing only the elements for which `someFn` returns `true`, and then sums up the length of this new array.

**Pros and Cons**

### Reduce

Pros:

* More efficient in terms of memory usage, as it avoids creating an intermediate array.
* Can be more efficient if the filtering condition is complex or expensive to evaluate.

Cons:

* May be slower due to the overhead of the `reduce()` method's accumulation step.
* Requires a callback function to define the accumulator and termination conditions.

### Filter

Pros:

* Often faster than `reduce` for simple filtering cases, as it avoids the accumulation step.
* More straightforward to implement and understand.

Cons:

* Creates an intermediate array, which can consume more memory.
* May be slower if the filtering condition is complex or expensive to evaluate.

**Library**

The benchmark uses the `someFn` function, which relies on the following libraries/syntax features:

* No external libraries are required, as `someFn` is a custom function defined within the script preparation code.
* JavaScript syntax features are used to define and call `someFn`, including arrow functions (`=>`) and the conditional operator (`? :`).

**Special JS Feature/Syntax**

The benchmark uses several special JavaScript features/syntax:

* Arrow functions (`=>`)
* Conditional operator (`? :`)
* Template literals (e.g., `"test-name" + i`)
* Array iteration syntax (e.g., `for (var i = 0; i < 12345; i++)`)

These features are used to define the custom function `someFn`, create the array, and iterate over its elements.

**Other Alternatives**

Other alternatives for filtering and summing arrays in JavaScript include:

* Using `Array.prototype.forEach()` with a callback function
* Using `Array.prototype.map()` with a callback function
* Using a library like Lodash or Underscore.js for more complex filtering and mapping operations

However, MeasureThat.net specifically compares the performance of `reduce` and `filter`, so these alternatives are not considered in this benchmark.

Related benchmarks:

Filter vs reduce objects test 12312412412 (version: 0)

Comparing performance of: reduce vs filter

Created: 3 years ago by: Guest

Jump to the latest result

reduce

filter

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):