Benchmark: reassigning an object

Script Preparation code:

var array = [{
        id: 1,
        name: 'Item 1'
    },
    {
        id: 2,
        name: 'Item 2'
    },
    {
        id: 3,
        name: 'Item 3'
    }
];

var newObject = {
    id: 2,
    name: 'Updated Item 2'
};

Tests:

map
var index = array.findIndex(item => item.id === newObject.id); if (index !== -1) { array[index] = newObject; }
index
var index = array.findIndex(item => item.id === newObject.id); // Only proceed if the item is found var updatedArray; if (index !== -1) { updatedArray = [ ...array.slice(0, index), // Elements before the updated item newObject, // The updated item ...array.slice(index + 1) // Elements after the updated item ]; } else { // If the item isn't found, the array remains unchanged updatedArray = array; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
index

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/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
map	7028267.5 Ops/sec
index	4574258.5 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmarking test case, which measures the performance of two approaches: using `map()` and using an index to replace a specific element in an array.

**Options Compared**

Two options are compared:

1. **Using `map()`**: This approach creates a new array by mapping each element in the original array to a new value. In this case, it replaces the existing elements with a new object.
2. **Using an index to replace an element**: This approach uses the `findIndex()` method to find the index of the element that needs to be replaced and then creates a new array by concatenating the elements before, after, and the updated element.

**Pros and Cons**

### Using `map()`

Pros:

* Concise and expressive code
* Easy to read and maintain

Cons:

* Creates a new array, which can be memory-intensive for large datasets
* May have performance overhead due to array creation and iteration

### Using an index to replace an element

Pros:

* Avoids creating a new array, reducing memory usage
* Can be more efficient than `map()` for large datasets

Cons:

* Code is more verbose and complex
* Requires careful handling of edge cases (e.g., null or undefined elements)

**Library**

In the provided code, the `findIndex()` method is used to find the index of the element that needs to be replaced. This method is part of the Array prototype in JavaScript and is not a separate library.

**Special JS Feature/Syntax**

No special JavaScript features or syntax are used in this benchmark.

**Alternative Approaches**

Other approaches to replace an element in an array include:

1. **Using `splice()`**: Replaces elements by removing and inserting at the specified index.
2. **Using a loop**: Iterates over the array, finding and replacing the desired element using indexing or iteration.
3. **Using a library like Lodash**: Provides a `set` function that replaces elements in an array.

Each approach has its own trade-offs in terms of performance, memory usage, and code complexity. The choice of approach depends on the specific requirements and constraints of the use case.

**Benchmark Preparation Code Explanation**

The script preparation code creates an initial array with three elements and a new object `newObject`. This setup is used to test the two approaches: using `map()` and using an index to replace an element.

The individual test cases are defined in the JSON array, each specifying the benchmark definition, test name, and execution settings.

Related benchmarks:

reassigning an object (version: 0)

Comparing performance of: map vs index

Created: 2 years ago by: Guest

Jump to the latest result

map

index

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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