Benchmark: Spread operator vs array.map

HTML Preparation code:


<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Script Preparation code:

permutations = new Array(10000).map(() => ({ pagination: 'blah blah blah' }));
function updatePagination(action, prev) {
  return action;
}
action = 'something else';
state = { data: { permutations: [] } };
index = 5;

Tests:

Spread operator
const updated = [...permutations]; return { ...state, data: { ...state.data, permutations: updated } };
Spread operator v2
const updated = permutations.map(p => p); return { ...state, data: { ...state.data, permutations: updated } };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread operator
Spread operator v2

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.

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

The provided JSON represents a benchmark test case that compares two approaches for updating an object using the spread operator and Array.map. Here's what's being tested:

**Approaches being compared:**

1. **Spread operator (`[...permutations]`)**: This approach creates a new array by spreading the elements of `permutations`. The updated value is then returned as an object.
2. **Array.map (`permutations.map(p => p)`)**: This approach uses Array.prototype.map to create a new array with the same values as `permutations`.

**Pros and Cons of each approach:**

1. **Spread operator (`[...permutations]`)**:
	* Pros:
		+ Generally faster than Array.map, especially for large arrays.
		+ Can be more concise and readable for simple updates.
	* Cons:
		+ May not work as expected with complex objects or nested arrays.
		+ Can lead to new memory allocations if the spread operator creates a new array object.
2. **Array.map (`permutations.map(p => p)`)**:
	* Pros:
		+ Works well with complex objects and nested arrays.
		+ Returns a new array, which can be useful for further processing or transformations.
	* Cons:
		+ Typically slower than the spread operator, especially for large arrays.

**Library used:**

The benchmark uses Lodash (version 4.17.5), a popular JavaScript utility library that provides various functions for working with arrays, objects, and more. In this case, the `lodash.min.js` file is included in the HTML preparation code to ensure that the spread operator's behavior is consistent across browsers.

**Special JS feature or syntax:**

The benchmark uses the rest parameter syntax (`action = 'something else';`) and destructuring assignment (`state = { data: { permutations: [] } };`). These features are widely supported by modern JavaScript engines, but if you're targeting older browsers, you may need to use a polyfill or workarounds.

**Other alternatives:**

If you'd like to explore alternative approaches or libraries, here are some options:

1. **Object.assign()**: This method is used to merge two objects and assign their properties to an object.
2. **Object.create()**: This method creates a new object and returns it, which can be useful for creating prototypes or cloning objects.
3. **Array.prototype.slice()**: This method creates a shallow copy of an array.

These alternatives may not offer the same performance benefits as the spread operator or Array.map, but they can provide different trade-offs in terms of readability, conciseness, and functionality.

Related benchmarks:

Spread operator vs array.map (version: 0)

A comparison of the performance of the spread operator, [ ...array ], vs. Array.map(i => ...) and

Comparing performance of: Spread operator vs Spread operator v2

Created: 3 years ago by: Guest

Jump to the latest result

Spread operator

Spread operator v2

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):