Benchmark: JS String '+' short v.s. long strings

Script Preparation code:

var nLoops = 1000;
var shortString = "aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ"; // 52 characters
var longString = '';

for (var i = 0; i < 40; i++) {
  longString += shortString; // 52 characters x 40 = 2,080 characters
}

Tests:

Add short string each loop
var str = ''; for (var i = 0; i < nLoops; i++) { str += shortString; }
Add long string each loop
var str = ''; for (var i = 0; i < nLoops; i++) { str += longString; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Add short string each loop
Add long string each loop

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
Add short string each loop	378144.7 Ops/sec
Add long string each loop	371561.7 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation.

**Benchmark Purpose**

The benchmark tests whether the size of the string concatenated affects the performance of JavaScript. In other words, it measures how fast two different approaches are when concatenating strings:

1. Adding short strings repeatedly (one at a time) vs.
2. Building up long strings by repeating a short string multiple times.

**Options Compared**

The benchmark compares two options:

* Option 1: "Add short string each loop" - This approach involves concatenating short strings one at a time, using the `+` operator to concatenate strings.
* Option 2: "Add long string each loop" - This approach involves building up a long string by repeating a short string multiple times.

**Pros and Cons**

Both approaches have their trade-offs:

* **Option 1 (Add short string each loop)**:
	+ Pros:
		- Less memory allocation, as only a small amount of data is stored in the `str` variable at any given time.
		- May be faster due to reduced overhead of building up large strings.
	+ Cons:
		- More iterations required to build up the same length string, which can lead to increased execution time.
* **Option 2 (Add long string each loop)**:
	+ Pros:
		- Fewer iterations required to build up a given length string, potentially leading to faster execution times.
	+ Cons:
		- More memory allocation, as large amounts of data are stored in the `str` variable.

**Library and Purpose**

The benchmark uses no external libraries. It only relies on JavaScript's built-in functionality to concatenate strings.

**Special JS Features or Syntax**

There is no special JavaScript feature or syntax used in this benchmark.

**Other Considerations**

When building up large strings, it's essential to consider the following:

* **String interning**: In JavaScript, repeated concatenation of identical strings can lead to string interning, where multiple variables referencing the same string are stored in a single location. This optimization can impact performance.
* **Memory allocation and deallocation**: Frequent memory allocation and deallocation can incur overhead costs, especially when dealing with large amounts of data.

**Alternative Approaches**

For building up long strings, alternative approaches might include:

1. Using `Array.prototype.join()` or a similar method to concatenate an array of strings into a single string.
2. Utilizing Web Workers or other parallel processing techniques to take advantage of multi-core processors.
3. Leveraging specialized libraries or frameworks that optimize string concatenation and building processes.

In conclusion, the benchmark tests whether adding short strings repeatedly affects performance compared to building up long strings by repeating a short string multiple times. The results can provide insight into how JavaScript handles string concatenation and allocation, which is essential for optimizing applications that involve frequent string manipulation.

Related benchmarks:

JS String '+' short v.s. long strings (version: 0)

Does the size of the string concatenated affect the performance?

Comparing performance of: Add short string each loop vs Add long string each loop

Created: 2 years ago by: Guest

Jump to the latest result

Add short string each loop

Add long string each loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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