Benchmark: String concatenation vs array join vs array reduce

Script Preparation code:

var str = "";
var i;
var sArr = [];

Tests:

String concatentation
for (i = 1000; i > 0; i--) { str += "String concatenation. "; }
Array join
for (i = 1000; i > 0; i--) { sArr[i] = "String concatenation. "; } str = sArr.join("");
Array join (w/ push)
for (i = 1000; i > 0; i--) { sArr.push("String concatenation. "); } str = sArr.join("");
Array reduce
for (i = 1000; i > 0; i--) { sArr[i] = "String concatenation. "; } str = sArr.reduce((a, v) => a += `${v} `, '');
Array reduce trim
for (i = 1000; i > 0; i--) { sArr[i] = "String concatenation. "; } str = sArr.reduce((a, v) => a += `${v} `, '').trim();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String concatentation
Array join
Array join (w/ push)
Array reduce
Array reduce trim

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
String concatentation	2275.4 Ops/sec
Array join	7783.4 Ops/sec
Array join (w/ push)	87.0 Ops/sec
Array reduce	8.7 Ops/sec
Array reduce trim	16.3 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested on the provided JSON benchmark.

The benchmark is testing three different approaches to concatenate strings in JavaScript:

1. **String Concatenation**: This involves using the `+` operator to concatenate two or more strings together. In this case, it's done using a traditional loop that appends a string to another variable.
2. **Array Join**: Instead of concatenating strings directly, an array is created with each concatenated string as an element. Then, the `join()` method is used to concatenate all elements in the array into a single string.
3. **Array Reduce**: An array is created with each concatenated string as an element, and then the `reduce()` method is used to concatenate all elements in the array into a single string.

Let's examine each approach:

**Pros and Cons:**

* **String Concatenation**:
	+ Pros: Simple and widely supported.
	+ Cons: Can lead to performance issues due to string object creation and concatenation.
* **Array Join**:
	+ Pros: Efficient, as it avoids creating intermediate strings.
	+ Cons: May require additional memory for the array, especially for large datasets.
* **Array Reduce**:
	+ Pros: Memory-efficient, as it only requires a single variable to store the result.
	+ Cons: May be slower than other approaches due to function call overhead.

**Library and Special JS Features:**

None of the test cases appear to use any specific libraries or special JavaScript features beyond standard ECMAScript syntax.

**Other Alternatives:**

1. **Template Literals**: A newer syntax feature introduced in ECMAScript 2015, which allows for more readable string concatenation using template literals (e.g., `const str = 'String concatenation. ';`).
2. **Concatenation with Spread Operator**: Another recent syntax feature that allows for concise string concatenation using the spread operator (e.g., `const sArr = ['String concatenation. ', 'another string']; const str = sArr.join('');`).

Keep in mind that these alternatives may not be supported by older browsers or JavaScript engines.

Now, if you have any specific questions about this benchmark or its results, feel free to ask!

Related benchmarks:

String concatenation vs array join vs array reduce (version: 0)

Comparing performance of: String concatentation vs Array join vs Array join (w/ push) vs Array reduce vs Array reduce trim

Created: 4 years ago by: Guest

Jump to the latest result

String concatentation

Array join

Array join (w/ push)

Array reduce

Array reduce trim

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):