Benchmark: flatMap vs for...of

Script Preparation code:

xs = new Array(1000).fill("world")

Tests:

flatMap
xs.flatMap((x) => ["hello", x])
for of
const out = [] for (const x of xs) { out.push("hello"); out.push(x); } return out
forEach
const out = [] xs.forEach( (x) => { out.push("hello"); out.push(x); }) return out;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
flatMap
for of
forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Windows

View result in a separate tab

Test name	Executions per second
flatMap	33474.2 Ops/sec
for of	172641.9 Ops/sec
forEach	77270.0 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 provided benchmark measures the performance difference between three approaches: `flatMap`, `for...of`, and `forEach` in JavaScript.

**Script Preparation Code**

The script preparation code is used to create an array `xs` with 1000 elements, each containing the string "world". This array will be used as input for the benchmark.

**Html Preparation Code**

There is no HTML preparation code provided, which means that the benchmark only tests the JavaScript code without any DOM-related overhead.

**Test Cases**

The benchmark consists of three test cases:

1. **`flatMap`**: Tests the `flatMap` method, which flattens an array and returns a new array with the results.
2. **`for...of`**: Tests the `for...of` loop, which iterates over an array and executes a block of code for each element.
3. **`forEach`**: Tests the `forEach` method, which iterates over an array and executes a callback function for each element.

**Library Used**

None of the test cases use any external libraries.

**JavaScript Features/Syntax**

* None of the test cases use any special JavaScript features or syntax.

**Approach Comparison**

The three approaches are compared in terms of their performance:

1. **`flatMap`**: This approach is likely to be faster because it uses a single iteration over the array and avoids creating multiple intermediate arrays.
2. **`for...of`**: This approach creates an additional array `out` to store the results, which may incur overhead due to array creation and push operations.
3. **`forEach`**: Similar to `for...of`, this approach also creates an additional array `out` to store the results.

**Pros and Cons of Each Approach**

* **`flatMap`**:
	+ Pros: likely to be faster, fewer intermediate arrays created
	+ Cons: may not work as expected if the inner array is large or complex
* **`for...of`**:
	+ Pros: can handle large or complex arrays, easy to understand and implement
	+ Cons: creates an additional array `out`, potential overhead due to array creation and push operations
* **`forEach`**:
	+ Pros: similar to `for...of`, handles large or complex arrays well
	+ Cons: also creates an additional array `out`, same potential overhead as `for...of`

**Other Alternatives**

In addition to these three approaches, other alternatives for iterating over an array in JavaScript include:

1. **`map`**: Similar to `flatMap`, but returns a new array instead of flattening the original array.
2. **`reduce`**: Accumulates values in an array and applies a callback function to each element.

However, these alternatives may not be as suitable for this specific benchmark, which only tests the performance difference between three basic approaches.

Related benchmarks:

flatMap vs for...of (version: 0)

Comparing performance of: flatMap vs for of vs forEach

Created: 4 years ago by: Guest

Jump to the latest result

flatMap

for of

forEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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