Benchmark: String concatenation vs array join, 10 iterations

Script Preparation code:

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

Tests:

String concatentation
for (i = 10; i > 0; i--) { str += "String concatenation. "; }
Array join
for (i = 10; i > 0; i--) { sArr[i] = "String concatenation. "; } str = sArr.join("");
Array join (w/ push)
for (i = 10; i > 0; i--) { sArr.push("String concatenation. "); } str = sArr.join("");

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 world of JavaScript microbenchmarks!

**What is tested?**

The provided JSON represents a benchmark test case that compares three approaches for string concatenation:

1. **String Concatenation**: Directly appending strings using the `+` operator or the `+=` assignment.
2. **Array Join**: Using the `join()` method on an array of strings to concatenate them.
3. **Array Join with Push**: Similar to Array Join, but using the `push()` method to add elements to the array instead.

**Options compared**

These three approaches are being tested because they have different performance characteristics:

* **String Concatenation**: This approach is simple and easy to understand, but it can be inefficient due to the creation of temporary strings.
* **Array Join**: Using an array to concatenate strings can be more efficient than string concatenation, as the browser's JavaScript engine can optimize the process. However, this approach still creates a new string object, which may incur some overhead.
* **Array Join with Push**: This variation uses the `push()` method to add elements to the array, similar to Array Join. The difference lies in how the strings are stored and processed.

**Pros and Cons of each approach**

* **String Concatenation**:
	+ Pros: Simple, easy to understand.
	+ Cons: Can be inefficient due to temporary string creation.
* **Array Join**:
	+ Pros: Can be more efficient than string concatenation, as the browser's engine can optimize it. Also, arrays are generally more cache-friendly.
	+ Cons: Creates a new string object, which may incur some overhead.
* **Array Join with Push**:
	+ Pros: Similar to Array Join, but uses `push()` instead of indexing. This might be slightly faster due to reduced function call overhead.
	+ Cons: Requires an array and may have additional overhead due to the dynamic addition of elements.

**Library/dependency**

None mentioned in this benchmark definition.

**Special JS feature/syntax**

* **Template literals**: Not used in any of these test cases. Template literals are a relatively recent feature introduced in ES6 (ECMAScript 2015) and allow for more readable string interpolation using backticks (`).

**Other alternatives**

If you were to add more variations, you might consider:

* Using `Array.prototype.reduce()` or `Array.prototype.forEach()` instead of Array Join.
* Comparing different concatenation strategies, such as using a loop with indexing (e.g., `str += sArr[i]`) versus the `+=` assignment.

Keep in mind that these alternatives would likely have similar performance characteristics to the original approaches tested here.

Now that we've explored this benchmark test case, you should have a better understanding of how JavaScript engines optimize string concatenation and array manipulation.

Related benchmarks:

String concatenation vs array join, 10 iterations (version: 0)

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

Created: 4 years ago by: Registered User

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):