Benchmark: JS: String '+' v.s. join

Script Preparation code:

var initialStr = "aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ";
var initialSuffix = 123456789;
var nLoops = 100;

Tests:

+
var str = ''; var suffix = initialSuffix; for (var i = 0; i < nLoops; i++, suffix *= 100) { str += initialStr + suffix; }
join
var stringArray = []; var suffix = initialSuffix; for (var i = 0; i < nLoops; i++, suffix *= 100) { stringArray.push(initialStr + suffix); } stringArray.join('');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
+
join

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/109.0

Browser/OS: Firefox 109 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
+	83439.3 Ops/sec
join	48078.3 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The benchmark tests two approaches for concatenating strings in JavaScript: using the `+` operator and using the `join()` method.

**Script Preparation Code**

The script preparation code defines the following variables:

* `initialStr`: a string containing a large set of characters repeated 26 times
* `initialSuffix`: an initial suffix value used to increment the concatenation result
* `nLoops`: the number of iterations for each test case (100)

**Test Cases**

There are two test cases:

1. **`+`**: This test case uses a simple loop to concatenate `initialStr` with `initialSuffix` using the `+` operator.
2. **`join()`**: This test case creates an array of strings by concatenating `initialStr` with `initialSuffix` and then calls the `join()` method on the array with an empty string as the separator.

**Library Used**

In this benchmark, no external library is used. The `+` operator and the `join()` method are built-in JavaScript functions.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax used in this benchmark. It only uses standard JavaScript syntax for concatenation and array manipulation.

**Options Compared**

The two test cases compare the performance of using the `+` operator versus the `join()` method for concatenating strings.

**Pros and Cons of Each Approach**

* **Using the `+` operator:**
	+ Pros:
		- Simple and easy to understand
		- Fast execution
	+ Cons:
		- Can be slow for large strings due to string duplication
		- May lead to memory issues if not done correctly (e.g., using `String.prototype.repeat()` instead of repeating the entire string)
* **Using the `join()` method:**
	+ Pros:
		- Fast execution
		- Reduces memory overhead compared to concatenating strings directly
	+ Cons:
		- May have a higher overhead due to creating an array and calling `join()`
		- Less intuitive for some developers

**Other Considerations**

* The use of `initialSuffix` is likely used to increment the concatenation result, making it more comparable between test cases.
* Using `String.prototype.repeat()` instead of repeating the entire string could improve performance but may not be supported in older browsers.

**Alternative Approaches**

Some alternative approaches for concatenating strings include:

* Using `StringBuilder` or `TextBlob`: These libraries provide a more efficient way to concatenate strings, especially for large amounts.
* Using `Array.prototype.concat()`: This method can be used instead of `join()` if the separator is not empty.
* Using template literals (introduced in ECMAScript 2015): Template literals provide a concise way to concatenate strings with variables.

Keep in mind that these alternatives may have different performance characteristics and are more complex than using the `+` operator or `join()`.

Related benchmarks:

JS: String '+' v.s. join (version: 0)

Comparing performance of: + vs join

Created: 2 years ago by: Guest

Jump to the latest result

+

join

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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