Benchmark: Testing loops performance

Script Preparation code:

var i, values = [], sum = 0;
for (i = 0; i < 10000; i++) values[i] = i;

Tests:

For loop, decrementing
for (i = values.length; i--;) sum += values[i];
For loop, incrementing
for (i = 0; i < values.length; i++) sum += values[i];
forEach
values.forEach(function(value) { sum += value });
For loop, incrementing, cache length
var len = values.length; for (i = 0; i < len; i++) sum += values[i];
Different for
for (i in values) sum += values[i]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For loop, decrementing
For loop, incrementing
forEach
For loop, incrementing, cache length
Different for

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents a JavaScript benchmark test case on MeasureThat.net. The goal of this test is to measure the performance of different for loops in adding up the values of an array.

**Options Compared**

The benchmark compares four different approaches:

1. **For loop, decrementing**: `for (i = values.length; i--;) sum += values[i];`
2. **For loop, incrementing**: `for (i = 0; i < values.length; i++) sum += values[i];`
3. **forEach**: `values.forEach(function(value) { sum += value });`
4. **For loop, incrementing, cache length**: `var len = values.length; for (i = 0; i < len; i++) sum += values[i];`

**Pros and Cons of Each Approach**

1. **For loop, decrementing**: This approach has a fixed number of iterations, which can be efficient in terms of memory usage. However, it may not be the most readable or maintainable option.
2. **For loop, incrementing**: This is a common and straightforward approach that iterates over the array using an index variable. It's easy to understand but might lead to off-by-one errors if not handled carefully.
3. **forEach**: The `forEach` method provides a concise way to iterate over an array without having to manage an index variable. However, it may be less efficient than the other approaches due to additional overhead from the iteration mechanism.
4. **For loop, incrementing, cache length**: This approach uses a separate variable to store the length of the array and then iterates using that value. It can improve performance by avoiding the overhead of calculating the array length at each iteration.

**Library Usage**

The benchmark uses JavaScript's built-in `forEach` method, which is implemented in the browser engine (in this case, Opera). The `forEach` method provides a concise way to iterate over an array without having to manage an index variable.

**Special JS Feature or Syntax**

None of the test cases use any special JavaScript features or syntax that would require additional explanation. All the approaches are standard and widely supported in modern browsers.

**Other Alternatives**

Alternative approaches could include:

1. **Using `Array.prototype.forEach.call()`**: This method is similar to the `forEach` method but requires a separate call to ensure compatibility with older browsers.
2. **Using a custom loop function**: Implementing a custom loop function using a recursive or iterative approach can provide better control over performance and readability.
3. **Using parallel processing**: If the benchmark is designed for high-performance applications, considering parallel processing techniques (e.g., Web Workers) might be an alternative.

Keep in mind that the choice of implementation depends on the specific requirements of the project, such as performance, readability, and compatibility with different browsers or versions.

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.59 Safari/537.36 OPR/41.0.2353.46

Browser/OS: Opera 41 on Windows

View result in a separate tab

Test name	Executions per second
For loop, decrementing	174.4 Ops/sec
For loop, incrementing	139.3 Ops/sec
forEach	460.0 Ops/sec
For loop, incrementing, cache length	154.1 Ops/sec
Different for	189.1 Ops/sec

Related benchmarks:

Testing loops performance (version: 1)

Comparing performance of: For loop, decrementing vs For loop, incrementing vs forEach vs For loop, incrementing, cache length vs Different for

Created: 8 years ago by: Registered User

Jump to the latest result

For loop, decrementing

For loop, incrementing

forEach

For loop, incrementing, cache length

Different for

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):