Benchmark: edit map vs slice no index

Script Preparation code:

window.arr = new Array(2000).fill({value: 'old'});
arr[100] = {value: 'toReplace'};

Tests:

map
const editIndex = arr.findIndex(item => item.value === 'toReplace'); const newArr = arr.map((item, index) => index === editIndex ? {value: 'new'} : item);
slice
const editIndex = arr.findIndex(item => item.value === 'toReplace'); const newArr = [ ...arr.slice(0, editIndex), {value: 'new'}, ...arr.slice(editIndex + 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: 5 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.79 Safari/537.36

Browser/OS: Chrome 79 on Mac OS X 10.14.0

View result in a separate tab

Test name	Executions per second
map	119464.3 Ops/sec
slice	79249.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The benchmark is designed to compare the performance of two approaches: `map()` and `slice()`. The script preparation code creates an array `arr` with 2000 elements, fills it with objects, and then replaces one element's value. The HTML preparation code is empty in this case.

**Options Compared**

Two options are compared:

1. **`map()`**: This method creates a new array by iterating over the original array and applying a transformation function to each element.
2. **`slice()`**: This method returns a shallow copy of a portion of an array, skipping the specified number of elements before the start of the slice.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* `map()`:
	+ Pros: Creates a new array with the desired transformation, can be more efficient for large datasets.
	+ Cons: Can be slower than `slice()` for small datasets due to the overhead of creating a new array.
* `slice()`: 
	+ Pros: Faster for small datasets, as it only creates a shallow copy of the original array.
	+ Cons: Returns a reference to the original array, which can be problematic if the original array is modified.

**Library and Special Features**

Neither `map()` nor `slice()` use any external libraries. However, these methods do utilize JavaScript's built-in features:

* `map()`: Uses the Array.prototype.map() method, which was introduced in ECMAScript 2012 (ES6).
* `slice()`: Uses the Array.prototype.slice() method, which has been available since ECMAScript 1 (ES1).

**Other Considerations**

When choosing between `map()` and `slice()`, consider the following factors:

* Dataset size: For large datasets, `map()` might be more efficient due to its ability to create a new array. For small datasets, `slice()` is likely faster.
* Performance requirements: If high performance is critical, you may want to consider using a custom implementation that minimizes overhead.

**Other Alternatives**

If you're looking for alternative approaches, consider:

* Using a library like Lodash or Ramda, which provide more efficient and flexible ways of transforming arrays.
* Implementing your own custom array transformation function, which can be optimized for specific use cases.
* Considering other data structures, such as linked lists or trees, which may offer better performance characteristics for certain operations.

Keep in mind that these alternatives will depend on the specific requirements and constraints of your project.

Related benchmarks:

edit map vs slice no index (version: 0)

Which is faster?

Comparing performance of: map vs slice

Created: 5 years 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 2 months ago):