Benchmark: edit map vs slice

Script Preparation code:

window.editIndex = 1000;
window.arr = new Array(2000).fill({value: 'old'});

Tests:

Map
const newArr = arr.map((item, index) => index === editIndex ? {value: 'new'} : item);
Slice
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:

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**What is being tested?**

The test case measures the performance difference between two approaches to edit an array:

1. **Array.prototype.map()**: This method creates a new array with the results of applying a provided function on every element in the calling array.
2. **Array.prototype.slice()**: This method returns a shallow copy of a portion of an array.

**Options compared**

In this test case, two approaches are being compared:

1. `map()`
2. `slice()`

**Pros and Cons of each approach:**

**Array.prototype.map():**

Pros:

* More intuitive and readable code
* Less magic (no explicit indexing)
* Can be more efficient for larger arrays

Cons:

* Creates a new array, which can be memory-intensive
* Can be slower than slicing due to the creation of a new array

**Array.prototype.slice():**

Pros:

* Does not create a new array, reducing memory overhead
* Can be faster than mapping due to the reuse of existing array storage

Cons:

* Less intuitive and less readable code (due to explicit indexing)
* May require more manual indexing and calculation to handle edge cases

**Other considerations:**

* **Array length**: The test case uses an array of 2000 elements, which is a large dataset.
* **EditIndex**: The `editIndex` variable determines the point at which to edit the array. This value is set to 1000 in the benchmark preparation code.

**Test case library and features:**

The test case does not explicitly mention any libraries or special JavaScript features. However, it uses ES6 syntax (e.g., arrow functions, template literals) that may not be compatible with older browsers.

**Alternatives:**

Other alternatives to `map()` and `slice()` could include:

* Using a loop and manual indexing
* Using other array methods, such as `forEach()`, `every()`, or `some()`
* Using a third-party library or framework that provides optimized array operations

However, these alternatives may not be as efficient or readable as the original approaches.

In summary, this benchmark tests the performance difference between two common array editing techniques: `map()` and `slice()`. The test case highlights the trade-offs between creating a new array (using `map()`) versus reusing existing storage (using `slice()`).

Related benchmarks:

edit map vs slice (version: 0)

Which is faster for edition?

Comparing performance of: Map vs Slice

Created: 6 years ago by: Guest

Jump to the latest result

Map

Slice

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):