Benchmark: Spread vs Object.assign for mapping arrays into objects

Tests:

Spread
const data = [ ["test1", 1], ["test2", 2], ["test3", 3], ["test4", 4], ["test5", 5], ["test6", 6], ["test7", 7], ["test8", 8], ["test9", 9], ] const res = data.reduce((acc, item) => ({...acc, [item[0]]: item[1]}), {})
Object assign
const data = [ ["test1", 1], ["test2", 2], ["test3", 3], ["test4", 4], ["test5", 5], ["test6", 6], ["test7", 7], ["test8", 8], ["test9", 9], ] const res = data.reduce((acc, item) => {Object.assign(acc, {[item[0]]: item[1]}); return acc;}, {})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
Object assign

Fastest: N/A

Slowest: N/A

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

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Let's dive into the provided benchmark definition and test cases.

**Benchmark Definition:**
The benchmark measures the performance of two approaches for mapping arrays into objects:

1. Using the spread operator (`...`).
2. Using `Object.assign()`.

Both methods are used to create a new object by iterating over an array of key-value pairs, where each pair is extracted from the array and added as a property to the new object.

**Options Compared:**

* **Spread Operator (`...`)**: This method uses the spread operator to create a shallow copy of the array values, which are then used to initialize properties on the new object.
* **Object.assign()**: This method uses the `Object.assign()` method to merge multiple source objects into a target object. In this case, it's used to add each key-value pair from the array to the new object.

**Pros and Cons:**

* **Spread Operator (`...`)**:
	+ Pros: More concise and expressive syntax, easier to read and maintain.
	+ Cons: May have performance implications due to the creation of a shallow copy of the array values.
* **Object.assign()**:
	+ Pros: Can be more efficient for large datasets since it only copies the actual values from the sources.
	+ Cons: May require more code and is less expressive than the spread operator.

In general, if readability and conciseness are prioritized, the spread operator might be a better choice. However, if performance is a concern, using `Object.assign()` could be beneficial.

**Library and Purpose:**
None of the benchmarked methods rely on any specific libraries. They only use built-in JavaScript features.

**Special JS Feature or Syntax:**
Both methods utilize modern JavaScript syntax:

* Spread operator (`...`): introduced in ECMAScript 2015 (ES6)
* `Object.assign()`: also introduced in ECMAScript 2015 (ES6)

These features are widely supported by modern browsers, including Firefox 68.

**Alternative Approaches:**
Other approaches to mapping arrays into objects could include:

1. Using the `Array.prototype.reduce()` method with a custom callback function.
2. Utilizing a library like Lodash's `mapObject()` or `merge()` functions.
3. Implementing a simple loop-based approach using an array index and an object property.

These alternatives might have different performance characteristics, readability, or complexity compared to the spread operator and `Object.assign()` methods used in the benchmark.

Related benchmarks:

Spread vs Object.assign for mapping arrays into objects (version: 0)

Performance of spread vs Object.assign for mapping arrays into objects

Comparing performance of: Spread vs Object assign

Created: 6 years ago by: Guest

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Spread

Object assign

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):