Benchmark: JS join vs map - MeasureThat.net

Script Preparation code:

var array = [];
for (let i = 0; i < 100000; i++) {
  array.push(`item-${i}`);
}

Tests:

map
const arrayString = array.map((item, i) => [i > 0 && ", ", item]);
join
const arrayString = array.join(', ');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
join

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 18 on iOS 18.1

View result in a separate tab

Test name	Executions per second
map	1517.4 Ops/sec
join	706.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON benchmark definition and explain what is being tested, compared, and their pros and cons.

**Benchmark Definition**

The benchmark defines two test cases: `map` and `join`. Both tests are comparing two methods for concatenating strings in JavaScript:

1. `array.join(', ')`: This method joins all elements of the array into a single string, using a comma and space separator.
2. A custom implementation using the `map()` function, which is applied to each element of the array to create an array of strings with a separator.

**Options Compared**

The two options being compared are:

* **`array.join(', ')`: The built-in `join()` method**, which is a part of the JavaScript standard library. It's a concise and efficient way to concatenate arrays into strings.
* **Custom implementation using `map()`: A custom function that applies the concatenation logic to each element of the array**.

**Pros and Cons**

### Built-in `join()` Method

Pros:

* Concise and easy to read
* Efficient and optimized by the JavaScript engine
* Part of the standard library, so it's widely supported

Cons:

* Limited control over the separator and concatenation logic
* May not be suitable for all use cases (e.g., when you need a more complex separator or formatting)

### Custom Implementation using `map()`

Pros:

* More flexible and customizable than the built-in `join()` method
* Can handle complex separator and formatting requirements

Cons:

* More verbose and less readable than the built-in `join()` method
* May incur additional overhead due to function call and iteration

**Library Used**

The custom implementation uses the `map()` function, which is a part of the JavaScript standard library. The `map()` function applies a given function to each element of an array, returning a new array with the results.

**Special JS Feature/Syntax**

The test case uses the `const` keyword for variable declaration and assignment, which is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). It's used to declare variables that cannot be reassigned. In this benchmark, it's used to ensure that the custom implementation is executed in a specific context.

**Other Considerations**

When choosing between these two approaches, consider the following factors:

* Readability and maintainability: If you need to concatenate arrays frequently, using the built-in `join()` method might be more readable and easier to maintain.
* Control and customization: If you need more control over the separator and concatenation logic, or if you're working with complex formatting requirements, the custom implementation using `map()` might be a better choice.
* Performance: The built-in `join()` method is likely to be faster and more efficient than the custom implementation, as it's optimized by the JavaScript engine.

**Other Alternatives**

If you need even more control over string concatenation or require additional features, you can consider other alternatives:

* Using template literals (`template`): This feature allows you to embed expressions inside string literals, making it easier to concatenate variables.
* Using `Array.prototype.reduce()`: This method applies a given function to each element of an array, reducing the result to a single value.

Keep in mind that these alternatives might introduce additional overhead or complexity, depending on your specific use case.

Related benchmarks:

JS join vs map (version: 0)

Compare JS join and map methods.

Comparing performance of: map vs join

Created: 3 years ago by: Guest

Jump to the latest result

map

join

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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