Benchmark: Map vs preallocation vs push vs no fill

Script Preparation code:

var array = new Array(1000000).fill(0);

Tests:

Map
const array2 = array.map((item, index) => index);
Preallocation
const array2 = new Array(1000000).fill(0); for (let i = 0, len =array2.length ; i < len ; i++) array2[i] = i;
Push
const array2 = [] for (let i = 0, len = 1000000; i < len; i++) array2.push(i);
no fill
const array2 = new Array(1000000) for (let i = 0; i < array2.length; i++) array2[i] = i;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map
Preallocation
Push
no fill

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 explaining the benchmark and its various components.

**Benchmark Definition:**
The provided JSON represents a JavaScript microbenchmark that compares four different approaches to create an array:

1. `Map`: Using the `map()` method to create a new array with mapped values.
2. `Preallocation`: Creating an empty array of a specified length using `new Array()`, and then filling it with values using a loop.
3. `Push`: Using the `push()` method to add elements one by one to an existing array, starting from an empty array.
4. `no fill`: Similar to `preallocation`, but without preallocating the array with a specified length.

**Options Compared:**
The benchmark compares the performance of these four approaches in creating an array of 1 million elements.

**Pros and Cons of Each Approach:**

*   **Map**: Pros:
    *   Efficient, as it avoids unnecessary memory allocations.
    *   Simple to implement.
*   Cons:
    *   May incur additional overhead due to the use of a new array and function calls.

*   **Preallocation**: Pros:
    *   Reduces memory allocations, which can be expensive operations in JavaScript.
    *   Can lead to better performance, especially for large datasets.
*   Cons:
    *   Requires more code to create the preallocated array.
    *   May not be suitable for dynamic arrays with varying lengths.

*   **Push**: Pros:
    *   Simple and easy to implement.
    *   Suitable for dynamic arrays with varying lengths.
*   Cons:
    *   Involves multiple loop iterations, which can lead to performance overhead.
    *   Memory allocations may occur during the push operations.

*   `no fill`: This approach is similar to preallocation but without explicitly creating a new array. Instead, it relies on JavaScript's automatic memory management for arrays. The `no fill` option effectively mimics the behavior of the `preallocation` method by using the `new Array()` constructor with no arguments, which creates an empty array.

**Library and Its Purpose:**
The benchmark does not explicitly use any external libraries or frameworks beyond the standard JavaScript features. However, it relies on some built-in browser functionality for its execution environment:

*   The `map()`, `push()`, and other methods used in the benchmarks are standard JavaScript methods.
*   The `new Array()` constructor is a built-in function in JavaScript, used to create arrays with specific lengths.

**Special JS Features or Syntax:**
The benchmark does not explicitly use any special JavaScript features like async/await, `let` and `const` declarations, arrow functions, or ES modules. It primarily focuses on demonstrating the performance of basic array creation methods in a straightforward, easy-to-understand context.

**Alternatives:**
There are several alternatives to measuring the performance of this benchmark:

*   **Benchmarking Frameworks:** Utilizing established benchmarking frameworks like `benchmark.js`, `fast-bench`, or ` benchmark` (a built-in Node.js module) can simplify and enhance the benchmarking process.
*   **Profiling Tools:** Leverage browser profiling tools, such as Chrome DevTools' Profiler, Firefox's Performance Monitor, or Edge's DevTools, to analyze performance bottlenecks in web applications.
*   **JavaScript Engines Comparison:** Test JavaScript engines like V8 (used by Google Chrome), SpiderMonkey (used by Mozilla Firefox), and others for their execution speed and optimization efficiency.

These alternatives can provide a more comprehensive understanding of performance optimization techniques in JavaScript development.

Related benchmarks:

Map vs preallocation vs push vs no fill (version: 0)

Comparing performance of: Map vs Preallocation vs Push vs no fill

Created: 3 years ago by: Guest

Jump to the latest result

Map

Preallocation

Push

no fill

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):