Benchmark: for loop vs. .map anon2

Script Preparation code:

// Create sample data
var array = [1,2,3,4,5,6,7,8,9,0];
for (let i = 0; i< 100_000; i++) {
	array.push(i % 10);
}

var manipulateFn = num => {
	return num * 2 * 3;
}

Tests:

.map
var newArray = array.map( i => manipulateFn(i));
for loop
var newArray = []; for (let i=0; i<array.length; i++) { newArray.push(i *2 * 3); }
for loop with func
var newArray = []; for (let i=0; i<array.length; i++) { newArray.push(manipulateFn(i)); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.map
for loop
for loop with func

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Linux

View result in a separate tab

Test name	Executions per second
.map	90.3 Ops/sec
for loop	88.3 Ops/sec
for loop with func	42.7 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

This benchmark compares the performance of three methods for manipulating an array of numbers in JavaScript: using the `.map()` function, a traditional `for` loop, and a `for` loop that explicitly calls a separate function (`manipulateFn`). Below is a breakdown of each method, their pros and cons, relevant libraries or concepts, and alternative approaches.

### Benchmark Overview:

1. **Data Preparation**:
   - An array of numbers is created, and an additional 100,000 numbers (calculated with `i % 10`) are appended to this array.
   - The `manipulateFn` function is defined, which multiplies a number by 2 and 3 (effectively returning six times the input).

### Test Cases:

1. **`.map()` Method**:
   - **Benchmark Definition**: `var newArray = array.map(i => manipulateFn(i));`
   - **Test Name**: `.map`

**Pros**:
   - Functional approach: Can be easier to read and understand, particularly for those familiar with functional programming.
   - Chainable: Can be combined with other array methods (like `.filter()`, `.reduce()`) smoothly.
   
   **Cons**:
   - Performance may be slower in some cases compared to traditional loops, especially with larger datasets or more complex functions.
   - Implicit operation: It may introduce overhead because of the creation of a new function execution context for each element.

2. **`for` Loop**:
   - **Benchmark Definition**: `var newArray = []; for (let i = 0; i < array.length; i++) { newArray.push(i * 2 * 3); }`
   - **Test Name**: `for loop`

**Pros**:
   - Performance: Generally faster than `.map()` for simple operations since it avoids function overhead.
   - Greater control over the iteration process (e.g., easy to implement early exits, complex conditions).

**Cons**:
   - Imperative style may lead to less readable code, especially if the logic inside the loop is complex.
   - More prone to errors such as off-by-one mistakes.

3. **`for` Loop with `manipulateFn` Function**:
   - **Benchmark Definition**: `var newArray = []; for (let i = 0; i < array.length; i++) { newArray.push(manipulateFn(i)); }`
   - **Test Name**: `for loop with func`

**Pros**:
   - Code reusability: `manipulateFn` can be reused across different parts of the code, promoting modularity.
   - Improved readability for complex logic compared to inline logic in loops.
   
   **Cons**:
   - Slower than a direct calculation in the loop since it introduces function call overhead.
   - Greater risk of losing context if the function relies on external variables (not an issue here, but worth noting in other contexts).

### Benchmark Results:

From the benchmark results, we see the number of executions per second for each method:
- **`.map()`**: 90.32 executions/sec
- **`for loop`**: 88.29 executions/sec
- **`for loop with func`**: 42.67 executions/sec

This indicates that `.map()` and the traditional `for` loop perform similarly, both of which are significantly faster than using the function `manipulateFn` in a loop.

### Other Considerations:

- **Maintainability**: While performance is crucial, maintainability is equally important. Choosing the right approach depends on the specific context and the audience for the code.
- **Readability vs. Performance**: It’s often a trade-off; clean, readable code can sometimes lead to a decrease in performance. In critical applications where performance is paramount, profiling various methods may be necessary to make informed decisions.
- **Alternatives**: Other methods to manipulate arrays include:
  - Using `Array.prototype.reduce()` for more complex aggregation or transformations.
  - Libraries like **Lodash** can offer optimized utility functions that also focus on performance and usability.
  - **Typed Arrays**: If manipulating large datasets of numbers, JavaScript's typed arrays (like `Uint8Array`) can provide performance benefits.

In summary, the choice between these methods will hinge on the specific use case, performance requirements, and personal or team coding standards. Understanding the trade-offs will equip software engineers across levels of expertise to make informed decisions in their codebases.

Related benchmarks:

for loop vs. .map anon2 (version: 1)

Comparing performance of: .map vs for loop vs for loop with func

Created: one month ago by: Guest

Jump to the latest result

.map

for loop

for loop with func

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):