Benchmark: String concatenation vs array join 3

Script Preparation code:

var str = "";
var i;
var sArr = [];
for (i = 9999; i >= 0; i--) {
	sArr[i] = "String concatenation. ";
}

Tests:

String concatentation
for (i = 9999; i >= 0; i--) { str += sArr[i]; }
Array join
str = sArr.join("");
Array join (w/ push)
for (i = 0; i < 1000; i++) { str += sArr[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the explanation of what's being tested in this benchmark.

**Benchmark Overview**

The benchmark measures the performance difference between two approaches to concatenate strings: using the `+` operator (string concatenation) and using the `join()` method on an array (array join).

**Script Preparation Code**

The script preparation code sets up a variable `str` initialized as an empty string, an integer `i` starting from 9999, and an empty array `sArr`. The loop iterates from `i = 9999` down to `0`, appending the string "String concatenation. " to each element of `sArr` at index `i`.

**Benchmark Definitions**

There are three benchmark definitions, each corresponding to a different test case:

1. **String Concatenation**: The loop iterates from `i = 9999` down to `0`, appending the string "String concatenation. " to each element of `sArr` at index `i`. This is done using the `+` operator on the `str` variable.
2. **Array Join (original)**: The loop iterates from `i = 0` up to `9999`, pushing the string "String concatenation. " onto an empty array `sArr`. The `join()` method is then called on `sArr` with an empty string as its argument, effectively concatenating all elements of the array.
3. **Array Join (with push)**: The loop iterates from `i = 0` up to `9999`, pushing the string "String concatenation. " onto an empty array `sArr`. After the loop, `push()` is called on each element of `sArr` with the same string as its argument.

**Library and Syntax Used**

In this benchmark, the `join()` method is used on arrays. This is a built-in JavaScript method that concatenates all elements of an array into a single string.

No special JavaScript features or syntax are used in these test cases. The focus is solely on measuring the performance difference between string concatenation and array join.

**Performance Considerations**

When it comes to performance, both approaches have their pros and cons:

* **String Concatenation**: This approach can be efficient if you're working with a small number of strings because each operation creates a new string object. However, as you add more strings, the overhead of creating new objects increases, leading to slower performance.
* **Array Join (original)**: Using `join()` on an array is generally faster than concatenating individual strings because it avoids the overhead of creating new objects. This approach is more efficient when working with a large number of strings.

**Alternatives**

In terms of alternatives, there are other ways to concatenate strings in JavaScript:

* **Template literals**: Introduced in ECMAScript 2015, template literals provide a more efficient way to concatenate strings using the `$${}` syntax.
* **Array methods**: Other array methods like `reduce()` or `map()` can also be used to concatenate arrays into a single string.

However, these alternatives are not included in this benchmark. The focus is on comparing traditional string concatenation and array join using the most basic approaches.

Related benchmarks:

String concatenation vs array join 3 (version: 0)

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

Created: 3 years ago by: Guest

Jump to the latest result

String concatentation

Array join

Array join (w/ push)

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):