Benchmark: For vs For/Of vs foreach vs map

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){ someFn(item); })
for
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
map
arr.map(item => someFn(item))
for/of
for (var el of arr) { someFn(el); }

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:

No previous run results

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

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**Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided JSON represents a benchmark test case, which compares the performance of different loop constructs in JavaScript: `for`, `forEach`, `map`, and `for...of`.

**Loop Constructs Comparison**

The four loop constructs being compared are:

1. **Traditional `for` loop**: This is the most basic loop construct in JavaScript, where the loop variable is declared outside the loop body.
2. **`forEach` loop**: This loop construct iterates over an array using a callback function.
3. **`map` method**: This method creates a new array with the results of applying a provided function to each element of the original array.
4. **`for...of` loop**: This is a newer loop construct introduced in ECMAScript 2015, which iterates over an iterable object using a variable that takes on the value of each iteration.

**Pros and Cons**

Here's a brief summary of the pros and cons of each loop construct:

1. **Traditional `for` loop**:
	* Pros: Simple, efficient, and widely supported.
	* Cons: Can be error-prone, especially when dealing with complex iterations.
2. **`forEach` loop**:
	* Pros: Easy to use, concise, and well-suited for iterating over arrays.
	* Cons: May incur overhead due to the callback function.
3. **`map` method**:
	* Pros: Creates a new array with transformed elements, eliminating the need for manual iteration.
	* Cons: May incur higher memory overhead and slower performance compared to traditional loops.
4. **`for...of` loop**:
	* Pros: Modern, concise, and efficient, especially when dealing with iterable objects.
	* Cons: Less widely supported in older browsers and versions of JavaScript.

**Library: `someFn`**

The `someFn` function is a simple function that takes an integer `i` as input and returns the result of multiplying `i` by 3 and 8. This function is used to demonstrate the performance differences between the loop constructs.

**Special JS Feature: `let` and `const`**

Although not explicitly mentioned in the benchmark, using `let` or `const` instead of `var` can help improve performance and readability. In modern JavaScript, `let` and `const` are generally preferred over `var`.

**Other Alternatives**

If you're looking for alternative loop constructs, consider:

1. **`while` loop**: A traditional loop construct that iterates until a condition is met.
2. **`do...while` loop**: A variant of the `while` loop that executes the body before checking the condition.

However, these alternatives are not part of the standard JavaScript language and may incur additional overhead or complexity.

**Benchmark Results**

The latest benchmark results show that:

1. The `for...of` loop has the highest execution rate (9785.88 executions per second).
2. The `map` method has a lower execution rate compared to traditional loops.
3. The `forEach` loop and traditional `for` loop have similar performance, with slightly higher overhead due to the callback function or manual iteration.

Keep in mind that these results may vary depending on the specific use case and environment.

Related benchmarks:

For vs For/Of vs foreach vs map (version: 0)

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

Created: 5 years ago by: Guest

Jump to the latest result

foreach

for

map

for/of

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):