Benchmark: Copying data 2; mapping vs. spreading then modifying vs. Object.assign then modifiying

Script Preparation code:

var data = [{
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    }
];

Tests:

Mapping
data.map((d, i) => i === 2 ? ({...d, bar: { baz: "bye" } }) : d)
spreading, then modifying
const copy = [...data]; copy[2] = { ...copy[2], bar: { baz: "bye" } };
Object.assign, then modifying
const copy = Object.assign([], data) copy[2] = { ...copy[2], bar: { baz: "bye" } };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Mapping
spreading, then modifying
Object.assign, then modifying

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

**Benchmark Explanation**

The provided benchmark measures the performance of three different approaches for copying and modifying data in JavaScript:

1. **Mapping**: Uses the `Array.prototype.map()` method to create a new array with modified elements. In this case, the callback function checks if the index is equal to 2 and returns an object with the same properties as the original element, but with an additional "baz" property set to "bye".
2. **Spreading, then modifying**: Uses the spread operator (`...`) to create a shallow copy of the `data` array, and then modifies the third element of the copied array.
3. **Object.assign, then modifying**: Uses the `Array.prototype.slice()` method to create an empty array, which is then passed to `Object.assign()`, which copies properties from the original array to the new one. The modified property is added using the spread operator (`...`).

**Options Compared**

* Mapping: Creates a new array with modified elements.
* Spreading, then modifying: Creates a shallow copy of the original array and modifies it.
* Object.assign, then modifying: Creates an empty array and copies properties from the original array to it.

**Pros and Cons of Each Approach**

1. **Mapping**: Pros:
	* Efficient use of memory since only one array is created.
	* Easy to implement.
Cons:
	* May not work as expected for complex data structures or large arrays, since `map()` creates a new array in memory.
2. **Spreading, then modifying**: Pros:
	* Allows modification of original arrays without creating new ones.
	* Works well with shallow copies.
Cons:
	* Creates an additional copy of the original array, which can be inefficient for large arrays.
3. **Object.assign, then modifying**: Pros:
	* Works well with complex data structures or large arrays, since `Object.assign()` creates a deep copy.
	* Allows modification of properties in the copied object.

**Other Considerations**

* Performance: Mapping is generally faster than spreading and modifying, but slower than using `Object.assign()`.
* Memory usage: Spreading and modifying create additional copies of data, while mapping only uses memory for a single array.
* Code simplicity: Mapping is often the simplest approach to use.

**Library Used (if any)**

None explicitly mentioned in the benchmark definition. However, the test cases use standard JavaScript methods like `Array.prototype.map()`, spread operator (`...`), and `Object.assign()`.

**Special JS Features or Syntax**

No special features or syntax are used in this benchmark.

**Alternatives to Consider**

* Using a library like Lodash to simplify array operations.
* Using a more advanced data structure, like an object with nested properties, to test the performance of different copying and modifying approaches.
* Adding additional complexity to the test case, such as asynchronous operations or event handling, to simulate real-world scenarios.

Related benchmarks:

Copying data 2; mapping vs. spreading then modifying vs. Object.assign then modifiying (version: 0)

Comparing performance of: Mapping vs spreading, then modifying vs Object.assign, then modifying

Created: 3 years ago by: Guest

Jump to the latest result

Mapping

spreading, then modifying

Object.assign, then modifying

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):