Benchmark: String concatenation vs array join1

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(""); str = ""

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:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.67 Safari/537.36

Browser/OS: Chrome 87 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
String concatentation	4520.4 Ops/sec
Array join	10622.9 Ops/sec
Array join (w/ push)	12696.6 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is crucial for optimizing code and improving user experience.

The provided JSON represents a benchmark test on the website MeasureThat.net. The purpose of this benchmark is to compare three different approaches to concatenate strings in JavaScript: string concatenation using the `+` operator, array join using the `join()` method, and array push with subsequent indexing.

**Option Comparison**

1. **String Concatenation (`str += "String concatenation. ";`)**
	* Pros:
		+ Simple and easy to understand
		+ Fast execution time ( lowest in this benchmark)
	* Cons:
		+ Less efficient than other methods due to repeated allocations and copies of the string
2. **Array Join (`sArr.join("");`)**
	* Pros:
		+ Efficient as it avoids repeated allocations and copies by storing all strings in an array
3. **Array Push with Subsequent Indexing (`sArr.push("String concatenation. "); str = sArr.join("");`)**
	* Pros:
		+ Similar efficiency to array join, but also benefits from the `push()` method's fast insertion of elements into the end of the array
4. **No explicit loops or array operations** (not applicable in this benchmark)

Other alternatives that might be worth considering:

1. **Using a StringBuilder library**: A library like Lodash's `stringJoin()` or a custom implementation can improve performance by avoiding repeated allocations and copies.
2. **Using a dedicated string concatenation function**: Some libraries, such as FastString, provide optimized string concatenation functions that outperform the default JavaScript approach.

**Library Usage**

The benchmark uses the following libraries:

1. None explicitly stated (no additional libraries beyond the standard JavaScript API)
2. No special JS features or syntax are mentioned in this benchmark

However, it's worth noting that MeasureThat.net is designed to test specific aspects of JavaScript performance, and some optimizations might rely on browser-specific features or extensions.

**Benchmark Test Cases**

Each test case represents a different approach to string concatenation:

1. **String Concatenation (`str += "String concatenation. ";`)**: Simple and easy to understand, but less efficient.
2. **Array Join (`sArr.join("");`)**: Efficient by avoiding repeated allocations and copies.
3. **Array Push with Subsequent Indexing (`sArr.push("String concatenation. "); str = sArr.join("");`)**: Similar efficiency to array join, with additional benefits from the `push()` method's fast insertion of elements into the end of the array.

The benchmark results show that Array Join and Array Push with Subsequent Indexing are more efficient than string concatenation in this specific test case. However, the best approach depends on the specific use case, performance requirements, and code readability considerations.

Related benchmarks:

String concatenation vs array join1 (version: 0)

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

Created: 4 years ago by: Guest

Jump to the latest result

String concatentation

Array join

Array join (w/ push)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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