Benchmark: var len for/for in/forEach array sum

Script Preparation code:

var array = new Array(10000);
for (let i = 0; i < array.length; i++) {
  array[i] = i;
}

Tests:

for
let sum = 0; for (var i = 0, len = array.length; i < len; i++) { sum += array[i]; }
for each
let sum = 0; for (var item in array) { sum += item; }
forEach
let sum = 0; array.forEach(function(item, index) { sum += item; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
for each
forEach

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark JSON and explain what's being tested, compared, and their pros and cons.

**Benchmark Definition**

The benchmark is designed to measure the performance of three different ways to calculate the sum of an array:

1. `for` loop
2. `for each` loop (also known as iterating over an object's properties)
3. Array `forEach` method

These three approaches are being compared to determine which one is the most efficient.

**Script Preparation Code**

The script preparation code generates a large array of 10,000 elements and initializes its values from 0 to 9,999 using a `for` loop.

```javascript
var array = new Array(10000);
for (let i = 0; i < array.length; i++) {
  array[i] = i;
}
```

This code sets up the input data for the benchmark.

**Html Preparation Code**

There is no HTML preparation code provided, which means that this benchmark only tests the JavaScript engine's performance and does not take into account any browser-specific rendering or layout-related factors.

**Library Usage**

None of the benchmark test cases use any external libraries. The tests are designed to isolate the JavaScript engine's performance.

**Special JS Features or Syntax**

The `forEach` method is a built-in JavaScript function that was introduced in ECMAScript 5 (ES5). It allows iterating over an array without having to manually keep track of indices. However, this feature requires support for ES5 or later.

**Benchmark Results**

The latest benchmark results show the performance metrics for each test case:

* `forEach`: approximately 25,386 executions per second
* `for each`: approximately 3,428 executions per second
* `for`: approximately 1,631 executions per second

As you can see, the `forEach` method outperforms both the `for each` and `for` loops.

**Pros and Cons of Different Approaches**

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

* `for` loop:
	+ Pros: Well-established syntax, easy to understand, and works on older browsers that don't support ES5.
	+ Cons: Requires manual index management, which can lead to errors if not done correctly.
* `for each` loop (iterating over an object's properties):
	+ Pros: Easy to implement, especially for those familiar with iterating over objects.
	+ Cons: Not well-suited for arrays, as it relies on property names rather than indices. This can result in slower performance compared to the `forEach` method.
* Array `forEach` method:
	+ Pros: Modern syntax, easy to use, and optimized for performance by most JavaScript engines.
	+ Cons: Requires support for ES5 or later, which might not be available on older browsers.

**Other Alternatives**

If you need to calculate the sum of an array without using a loop, you could consider using:

* `reduce()` method: This is another built-in method that can be used to accumulate values in an array. While it's a more modern alternative to loops, its performance might not be as good as the optimized `forEach` method.
* Third-party libraries or frameworks: Depending on your specific use case, you might need to resort to using third-party libraries like Lodash or Underscore.js, which provide additional utility functions for array manipulation.

Keep in mind that these alternatives will add overhead due to their external dependencies, making them less suitable for performance-critical code.

Related benchmarks:

var len for/for in/forEach array sum (version: 0)

Comparing performance of: for vs for each vs forEach

Created: 3 years ago by: Guest

Jump to the latest result

for

for each

forEach

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):