Benchmark: forEach vs reduce vs map vs filter vs for vs for of

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,
  sumForOf = 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; j < arr.length; j++) { sumFor += someFn(arr[j]); }
forOf
for (const j of arr) { sumForOf += someFn(arr[j]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
reduce
map
filter
for
forOf

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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I'm ready to break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark measures the performance of six different JavaScript iteration methods:

1. `forEach`
2. `reduce`
3. `map`
4. `filter`
5. `for` loop
6. `for...of` loop

Each method is used to iterate over an array and calculate a value.

**Library Usage**

One library is used in this benchmark: Lodash's `_` function, which is not explicitly mentioned in the provided code. However, based on the context, it's likely that the `_` function from Lodash is being used as a utility function to provide `someFn(item)`.

**Special JavaScript Features/Syntax**

There are no special JavaScript features or syntax being tested in this benchmark.

**Comparison of Iteration Methods**

Here's a brief overview of each iteration method and their pros/cons:

1. **`forEach`**: Uses the `Array.prototype.forEach()` method, which iterates over an array using a callback function.
	* Pros: Simple to use, easy to read.
	* Cons: Can be less efficient than other methods because it uses a separate loop variable.
2. **`reduce`**: Uses the `Array.prototype.reduce()` method, which applies a reduction operation to each element in the array.
	* Pros: Efficient and concise, can perform multiple operations on the same data.
	* Cons: Can be less readable for complex logic, may require additional setup.
3. **`map`**: Uses the `Array.prototype.map()` method, which creates a new array with transformed values.
	* Pros: Easy to use, produces a new array with transformed values.
	* Cons: Creates an additional array object, can consume more memory.
4. **`filter`**: Uses the `Array.prototype.filter()` method, which creates a new array with filtered elements.
	* Pros: Efficient and concise, filters out unwanted data.
	* Cons: Creates an additional array object, can consume more memory.
5. **`for` loop**: Iterates over the array using a traditional `for` loop, incrementing a counter variable.
	* Pros: Low-level control, no dependency on browser or runtime features.
	* Cons: Can be error-prone, requires manual index management.
6. **`for...of` loop**: Iterates over the array using an enhanced `for` loop, which uses the iterator protocol.
	* Pros: Easy to use, concise, and readable.
	* Cons: Limited control over iteration flow.

**Other Alternatives**

Some alternative iteration methods not included in this benchmark include:

1. `every()`, `some()`: These methods can be used for filtering or testing conditions on individual elements.
2. `Array.prototype.every()`/`Array.prototype.some()`: These methods can be used to test conditions on all elements in the array.
3. Callback functions with manual loop management: This approach requires manually managing an index variable and looping through the array.

Overall, this benchmark provides a good starting point for understanding the performance differences between various iteration methods in JavaScript.

Related benchmarks:

forEach vs reduce vs map vs filter vs for vs for of (version: 0)

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

Created: 6 years ago by: Guest

Jump to the latest result

forEach

reduce

map

filter

for

forOf

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):