Benchmark: forEach vs reduce vs map vs filter vs for -- exlord

Script Preparation code:

var arr = [];
for (var i = 0; i < 12345; i++) {
  arr[i] = i;
}

function someFn(i) {
  return (i * 3 * 8 / 1200 * 0.002 / 40 * 0.2);
}

var sumForEach = 0,
  sumReduce = 0,
  sumMap = 0,
  sumFilter = 0,
  sumFor = 0;

Tests:

forEach
arr.forEach(item => sumForEach += someFn(item));
reduce
sumReduce = arr.reduce((lastValue, item) => { return sumReduce += someFn(item); });
map
arr.map(item => (sumMap += someFn(item)));
filter
arr.filter(item => (sumFilter += someFn(item)));
for
for (var j = 0,l=arr.length; j < l; j++) { sumFor += arr[j]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
reduce
map
filter
for

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

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Let's dive into the details of this benchmark.

**What is being tested?**

The test case compares the performance of five different methods to iterate over an array and perform some calculations:

1. `forEach`
2. `reduce`
3. `map`
4. `filter`
5. a traditional `for` loop

Each method is executed on an array of 12,345 elements, where each element is assigned a value from 0 to 12,344.

**What options are compared?**

The test case compares the performance of these five methods:

1. **forEach**: The `forEach()` method executes a provided function once for each element in an array.
2. **reduce**: The `reduce()` method applies a function against an accumulator and each value of the array (from left to right) to reduce it to a single output.
3. **map**: The `map()` method creates a new array with the results of applying a provided function on every element in this array.
4. **filter**: The `filter()` method creates a new array with all elements that pass the test implemented by the provided function.
5. **for** loop: A traditional `for` loop is used as a baseline for comparison.

**Pros and cons of each approach:**

1. **forEach**: Pros: Easy to read, intuitive API. Cons: Not suitable for reducing values (e.g., summing up an array).
2. **reduce**: Pros: Can be used to reduce values (e.g., summing up an array). Cons: Can be less readable than other methods.
3. **map**: Pros: Creates a new array with transformed values, can be used in conjunction with `forEach` or other methods. Cons: Not suitable for reducing values.
4. **filter**: Pros: Easy to use when filtering data. Cons: Not suitable for performing calculations on each element.
5. **for** loop: Pros: Low-level control over the iteration process. Cons: May be less readable than other methods.

**Other considerations:**

* The `forEach` method is generally faster than `reduce`, `map`, and `filter` because it doesn't require creating a new array.
* The `reduce` method can be more efficient when reducing values (e.g., summing up an array), but may be less readable than other methods.

**Library or special JS feature used:**

None in this case. The test uses only built-in JavaScript features and arrays.

**Alternative approaches:**

Other alternatives to consider when iterating over an array include:

* Using a `while` loop instead of a `for` loop
* Using a recursive function (not recommended due to performance issues)
* Using libraries like Lodash or Underscore.js for more advanced iteration methods

I hope this explanation helps!

Related benchmarks:

forEach vs reduce vs map vs filter vs for -- exlord (version: 0)

Comparing performance of: forEach vs reduce vs map vs filter vs for

Created: 5 years ago by: Guest

Jump to the latest result

forEach

reduce

map

filter

for

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):