Benchmark: Array loop vs foreach vs map populate array

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
    arr[i] = i;
}

var arr2 = [];

Tests:

foreach
arr.forEach(function (item){ arr2.push(item); })
for
for (var i = 0, len = arr.length; i < len; i++) { arr2.push(arr[i]); }
map
arr2 = arr.map(item => item)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map

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'll break down the provided benchmark and explain what's being tested, compared, and some pros/cons of each approach.

**Benchmark Overview**

The test measures the performance of three different approaches to populate an array:

1. Using `forEach` with a callback function
2. Using a traditional `for` loop
3. Using the `map()` method

**Options Compared**

Each test case compares two versions: one using the tested approach, and another as a baseline (the original code without any changes).

For example, in the first test case (`foreach`), there are two versions:

* The tested version: `arr.forEach(function(item) { arr2.push(item); })`
* The baseline version: The original code with an empty array `var arr = []`

The baseline version serves as a reference point to measure the overhead of using `forEach`.

**Pros and Cons of Each Approach**

1. **`forEach` with callback function**: This approach is concise and readable, but it can be slower than traditional loops because JavaScript engines need to call back into the loop from within the callback function.
	* Pros: Easy to read and write
	* Cons: Potential performance overhead due to callbacks
2. **Traditional `for` loop**: This approach is often faster and more efficient because it avoids the overhead of JavaScript engine calls.
	* Pros: Generally faster and more efficient
	* Cons: More verbose and less readable than other approaches
3. **`map()` method**: The `map()` method is a built-in array method that can be faster than traditional loops, but its performance depends on the specific use case and implementation details.
	* Pros: Can be faster in some cases, concise, and easy to read
	* Cons: May not work as expected if the loop conditions are complex

**Library Used**

None of the benchmark test cases rely on any external libraries.

**Special JS Feature/Syntax**

There is no special JavaScript feature or syntax used in these tests. The benchmark focuses solely on comparing different approaches to populate an array.

**Alternative Approaches**

Some alternative approaches to populate an array could include:

1. Using a `for...of` loop (not tested in this benchmark)
2. Using `reduce()` method
3. Using a closure or higher-order function

These alternatives may offer different performance characteristics and trade-offs, depending on the specific use case.

Keep in mind that these tests are designed to measure the relative performance of each approach, rather than providing an absolute measurement of their efficiency.

Related benchmarks:

Array loop vs foreach vs map populate array (version: 0)

Comparing performance of: foreach vs for vs map

Created: 5 years ago by: Guest

Jump to the latest result

foreach

for

map

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):