Benchmark: Map vs For Loop - MeasureThat.net

Script Preparation code:

var a = [];
for (var i = 0; i < 1e6; i++) {
  a[i] = Math.random();
}

Tests:

Map
var b = a.map(n => n * 2); return b;
For Loop
var b = []; for (var i = 0; i < a.length; i++) { b[i] = a[i] * 2; } return b;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map
For Loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Safari/605.1.15

Browser/OS: Safari 17 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Map	374.1 Ops/sec
For Loop	12.8 Ops/sec

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

LLMs can make mistakes. Check important info.

**What is being tested?**

The provided JSON represents a benchmark test case that compares the performance of two approaches to double each element in an array: using the `map()` function versus a traditional `for` loop.

**Options compared:**

1. **Map()**: The `map()` function is a built-in JavaScript method that creates a new array with the results of applying a provided function on every element in this array.
2. **For Loop**: A traditional `for` loop is used to iterate over each element in the array and manually double its value.

**Pros and Cons:**

*   **Map()**:
    *   Pros:
        *   More concise and readable code
        *   Easier to maintain and extend
        *   Handles errors and edge cases more elegantly
    *   Cons:
        *   May incur a higher overhead due to the creation of a new array
        *   Can be slower for very large arrays
*   **For Loop**:
    *   Pros:
        *   Can be faster for very large arrays, as it avoids creating a new array
        *   More control over iteration and edge cases
    *   Cons:
        *   More verbose code that may be harder to read and maintain
        *   May require more error handling

**Library used:**

None.

**Special JS feature or syntax:**

The `map()` function is a built-in JavaScript method, but it does utilize some underlying concepts like closures and dynamic property creation (via the `n => n * 2` arrow function). However, this is considered standard JavaScript features rather than special syntax or advanced features.

**Other alternatives:**

Other approaches to double each element in an array could include:

1.  **Reduce()**: Although not directly applicable here, `reduce()` can be used in conjunction with `map()` for more complex transformations.
2.  **Spreading and concatenation**: Using the spread operator (`...`) to create a new array by spreading the original array's elements, followed by concatenation or another method to double each element.

These alternatives might offer different performance characteristics depending on the use case and browser support.

In conclusion, the test compares two common approaches to transform an array in JavaScript: using `map()` versus a traditional `for` loop. The choice between these methods often depends on the specific requirements of the project, such as code readability, maintainability, and performance.

Related benchmarks:

Map vs For Loop (version: 1)

Comparing performance of: Map vs For Loop

Created: 9 years ago by: Registered User

Jump to the latest result

Map

For Loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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