Benchmark: update object at certain index in array .map() vs .slice()

Tests:

.map()
const list = [{name: 'john'}, {name: 'doe'}, {name: 'jane'}, {name: 'dee'}]; const targetIndex = 2; const updated = list.map((item, itemIndex) => { if (itemIndex === targetIndex) return {name: 'albert'}; return item });
.slice()
const list = [{name: 'john'}, {name: 'doe'}, {name: 'jane'}, {name: 'dee'}]; const targetIndex = 2; const updated = [...list.slice(0, targetIndex), {name: 'albert'}, ...list.slice(targetIndex + 1)]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.map()
.slice()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 13) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 113 on Android

View result in a separate tab

Test name	Executions per second
.map()	15921480.0 Ops/sec
.slice()	5940219.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition**

The provided JSON represents a benchmark test case that compares two approaches for updating an object at a certain index in an array: using `map()` versus `slice()`. The benchmark aims to determine which approach is faster, more efficient, and more suitable for such operations.

**Options Compared**

Two options are being compared:

1. **`map()`**: This method creates a new array with the results of applying a provided function on every element in this array. In this case, it's used to update the object at a specific index.
2. **`slice()`**: This method returns a shallow copy of a portion of an array into a new array object. It's also used to update the object at a specific index.

**Pros and Cons**

*   `map()`: 
    *   Pros:
        *   More straightforward and intuitive for updating objects in arrays.
        *   Can be more memory-efficient if the original array is not modified.
    *   Cons:
        *   Creates a new array, which might lead to increased memory usage and slower performance.
*   `slice()`: 
    *   Pros:
        *   More flexible, allowing for partial updates or modifications to existing elements.
        *   Can be more efficient when dealing with large arrays, as it doesn't require creating a new array.
    *   Cons:
        *   Requires manual indexing and concatenation, which can lead to increased overhead and slower performance.

**Library Usage**

In the benchmark test case, there is no explicit library usage. However, if we assume that the `Array.prototype` methods (`map()` and `slice()`) are part of a larger JavaScript framework or implementation, they can be considered as using built-in libraries for array manipulation.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax used in this benchmark test case. It only involves standard JavaScript array methods and variable assignments.

**Alternatives**

Other alternatives for updating an object at a certain index in an array might include:

*   **Using `forEach()`**: While not as efficient as `map()` or `slice()`, using `forEach()` can still be useful when dealing with smaller arrays.
*   **Using `reduce()`**: Similar to `map()`, but with the added benefit of accumulating a result that can be used throughout the iteration process.

To update an object at a specific index, one could use the following approaches:
*   Iterate over the array using `forEach()`, accessing each element's index and updating it manually.
*   Utilize libraries or modules for array manipulation, such as Lodash or Ramda, which provide more extensive functionality for working with arrays.

These alternatives are not part of the standard JavaScript syntax but can be useful in specific scenarios where customization is required.

Related benchmarks:

update object at certain index in array .map() vs .slice() (version: 0)

Comparing performance of: .map() vs .slice()

Created: one year ago by: Guest

Jump to the latest result

.map()

.slice()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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