Benchmark: Optional string concatenation vs array join

Script Preparation code:

var str = "";
var i;
var sArr = ["a", "b", null, false, "c"];

Tests:

String concatentation
for (i = 0; i <sArr.length; i++) { if (!sArr[i]) continue; if (str.length > 0) { str += " " + sArr[i]; } else { str = sArr[i]; } }
Filter then join
str = sArr.filter(Boolean).join(" ");
Filter then join 2
str = sArr.filter(v => !!v).join(" ");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String concatentation
Filter then join
Filter then join 2

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 the provided benchmark.

**Benchmark Overview**

The benchmark compares three approaches to concatenate strings in JavaScript:

1. String concatenation using the `+` operator
2. Using an array and the `join()` method
3. Filtering out falsy values from the array before joining with `join()`

**String Concatenation (Option 1)**

This approach uses a traditional loop to iterate through the array, appending each non-null value to the string using the `+` operator.

```javascript
for (i = 0; i <sArr.length; i++) {
  if (!sArr[i]) continue;
  if (str.length > 0) {
    str += " " + sArr[i];
  } else {
    str = sArr[i];
  }
}
```

Pros:

* Simple and easy to understand
* No additional dependencies required

Cons:

* Slow performance due to the loop and repeated concatenations
* May cause stack overflow errors for large arrays

**Filter then Join (Option 2)**

This approach uses the `filter()` method to remove falsy values from the array, followed by the `join()` method to concatenate the remaining elements with a space separator.

```javascript
str = sArr.filter(Boolean).join(" ");
```

Pros:

* Efficient and fast performance
* Reduces memory allocation and garbage collection

Cons:

* Requires JavaScript version support for `filter()` and `join()` methods
* May not be compatible with older browsers or environments

**Filter then Join 2 (Option 3)**

This approach is similar to Option 2, but uses an arrow function (`v => !!v`) instead of the `Boolean` function.

```javascript
str = sArr.filter(v => !!v).join(" ");
```

Pros:

* Same benefits as Option 2, with a slightly more concise syntax
* May be compatible with older browsers or environments

Cons: None significant compared to Option 2.

**Library and Special Features**

In the benchmark, the `filter()` method is used, which is a built-in JavaScript array method. There are no special features or libraries required for this benchmark.

**Alternative Approaches**

Other alternatives to compare string concatenation methods could include:

* Using a template engine like Handlebars or Pug
* Utilizing a library like Lodash for functional programming
* Employing a custom implementation using a different algorithm

However, the filter-join approach is a common and efficient way to concatenate strings in JavaScript, making it a suitable benchmark for this specific use case.

Related benchmarks:

Optional string concatenation vs array join (version: 0)

Comparing performance of: String concatentation vs Filter then join vs Filter then join 2

Created: 6 years ago by: Guest

Jump to the latest result

String concatentation

Filter then join

Filter then join 2

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):