Benchmark: string array join vs for loop concatenation

Script Preparation code:

var strings = Array(1000).fill('hola soy edu feliz navidad');

Tests:

For loop
let result = '' for(let i = 0; i < strings.length; i++) { result += strings[i] + '\n'; }
join
const result = strings.join('\n');

Historical Performance Data aggregated from 10 community runs

Desktop Results:

Chrome 10 runs

join

179K/s

For loop

136K/s

Fastest: join (1.3x faster)

View exact numbers

✓ join: 178,695 ops/sec
• For loop: 136,251 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For loop
join

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 23 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Firefox/140.0

Browser/OS: Firefox 140 on Windows

View result in a separate tab

For loop

110K/s

join

109K/s

View exact numbers

Test name	Executions per second
✓ For loop	110,054 Ops/sec
join	109,202 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is designed to compare two approaches for concatenating an array of strings in JavaScript:

1. **Join Method**: Using the `join()` method on the entire array, which returns a new string that concatenates all elements with the specified separator (in this case, `\n`).
2. **For Loop Concatenation**: Using a traditional `for` loop to iterate over the array and concatenate each element individually using the `+=` operator.

**Options Compared**

The benchmark compares these two approaches:

* **Join Method vs For Loop Concatenation**
	+ **Pros of Join Method**: More concise, efficient, and scalable for large arrays. It's a built-in method that's optimized for performance.
	+ **Cons of Join Method**: Can be slower for small arrays or when the separator is complex (e.g., requires multiple concatenations). Also, it returns a new string, which can lead to memory allocation issues in some cases.
	+ **Pros of For Loop Concatenation**: More control over each iteration, which can be beneficial for debugging and understanding the code. However, it's generally slower due to the overhead of creating an empty string and concatenating elements.
	+ **Cons of For Loop Concatenation**: More verbose, error-prone, and less scalable than the `join()` method.

**Library Used**

There is no specific JavaScript library mentioned in this benchmark. The `join()` method is a built-in method provided by the ECMAScript specification.

**Special JS Features or Syntax**

The benchmark uses the following special features:

* **Template Literals**: The `\r\n` escape sequence used in the `for` loop concatenation is an example of template literals, which were introduced in ECMAScript 2015.
* **Nullish Coalescing Operator (??)**: Not explicitly mentioned but not necessary here. This operator was also introduced in ECMAScript 2017.

**Alternative Approaches**

Some alternative approaches for string concatenation in JavaScript include:

1. **Array.prototype.forEach()**: Using `forEach()` instead of a `for` loop can be more concise and readable, especially when working with arrays.
2. **String.prototype.reduce()**: Using `reduce()` to concatenate an array of strings is another approach that's gained popularity in recent years.

However, these alternatives might not outperform the `join()` method for large arrays or performance-critical code.

I hope this explanation helps software engineers understand the benchmark and its purpose!

string array join vs for loop concatenation (version: 0)

Comparing performance of: `For loop vs join`

Created: one year ago by: Guest

Go to the latest result

For loop

join

Historical Performance Data aggregated from 10 community runs

Desktop Results:

Chrome 10 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

string array join vs for loop concatenation (version: 0)

Comparing performance of: For loop vs join

Created: one year ago by: Guest

Go to the latest result

For loop

join

Historical Performance Data aggregated from 10 community runs

Desktop Results:

Chrome 10 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Comparing performance of: `For loop vs join`