Benchmark: Array loop vs foreach vs map vs for of123

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = i;
    }
  
    function someFn(i) {
      return i * 3 * 8;
    }

Tests:

foreach
arr.forEach(function (item){ })
for
for (var i = 0, len = arr.length; i < len; i++) { arr[i] }
map
arr.map(item => item)
for of
for (var n of arr) { }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map
for of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36

Browser/OS: Chrome 85 on Windows

View result in a separate tab

Test name	Executions per second
foreach	1420818.2 Ops/sec
for	8684.6 Ops/sec
map	333952.1 Ops/sec
for of	931551.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what is tested, compared options, pros and cons, library usage, special JavaScript features, and alternatives.

**Benchmark Definition**

The provided JSON represents a benchmark that tests four different ways to iterate over an array in JavaScript:

1. `arr.forEach(function (item){...})`
2. `for (var i = 0, len = arr.length; i < len; i++) {...}`
3. `arr.map(item => item)`
4. `for (var n of arr) {...}`

The benchmark prepares an array with 1000 elements and a sample function `someFn(i)` that performs some calculation.

**Options Comparison**

Each test case compares a different iteration method:

* **`forEach`**: Iterates over the array using the `forEach` method, which calls a provided callback function for each element.
* **`for`**: Uses a traditional `for` loop to iterate over the array indices.
* **`map`**: Applies a transformation function to each element of the array using the `map` method.
* **`for...of`**: Iterates over the array elements using the `for...of` loop syntax.

**Pros and Cons**

Here's a brief summary of the pros and cons for each option:

* **`forEach`**:
	+ Pros: Simple, concise, and widely supported. It can also be used with other types of iterators.
	+ Cons: Can be slower than traditional loops due to the overhead of function calls.
* **`for`**:
	+ Pros: Fast, flexible, and allows direct access to array elements using indices.
	+ Cons: Requires manual index management, which can lead to errors.
* **`map`**:
	+ Pros: Concise, efficient, and returns a new array with transformed elements.
	+ Cons: Can be slower than traditional loops for large arrays due to the overhead of function calls. Also, it creates a new array, whereas `forEach` modifies the original.
* **`for...of`**:
	+ Pros: Modern, concise, and easy to read. It provides direct access to array elements using the `value` variable.
	+ Cons: Less widely supported than traditional loops, and its syntax is not as flexible.

**Library Usage**

None of the test cases use external libraries or frameworks.

**Special JavaScript Features**

The benchmark uses the following special JavaScript features:

* **`let`/`const`**: The code uses `var`, but it's worth noting that `let` and `const` are preferred for variable declarations in modern JavaScript.
* **Arrow functions**: The `map` test case uses arrow functions, which are a shorthand way to define small functions.
* **Template literals**: There is no explicit use of template literals in the code, but they can be used to create string-like objects.

**Alternatives**

Other alternatives for iterating over arrays include:

* **`reduce()`**: A reduction function that applies a callback function to each element and returns a single value.
* **`filter()`**: A filter function that creates a new array with elements that pass a provided test.
* **`every()`**, **`some()`**, or **`includes()`**: These methods can be used for conditional checks on arrays.

Keep in mind that the choice of iteration method depends on the specific use case and performance requirements. The `forEach`, `for`, and `map` methods are commonly used, while `for...of` is a more modern alternative.

Related benchmarks:

Array loop vs foreach vs map vs for of123 (version: 0)

Comparing performance of: foreach vs for vs map vs for of

Created: 4 years ago by: Guest

Jump to the latest result

foreach

for

map

for of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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