Benchmark: Object.assign vs spread vs custom assign

Script Preparation code:

function assign(a, b) {
	for (let i in b) a[i] = b[i];
	return (a);
}

Tests:

Object.assign
var params = { b:"hello", c: true, d:7 }; var other = Object.assign({ a: 2 }, params);
spread operator
var params = { b:"hello", c: true, d:7 }; var other = { a: 2, ...params };
custom assign
var params = { b:"hello", c: true, d:7 }; var other = assign({ a: 2 }, params);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign
spread operator
custom assign

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the benchmark and explain what is being tested, compared, and considered.

**Benchmark Overview**

The benchmark measures the performance of three different approaches to merge two objects: `Object.assign()`, spread operator (`...`), and a custom `assign()` function. The test case creates an object with properties `b`, `c`, and `d`, and then merges it with another object using each approach.

**Comparison**

Here's what is being compared:

1. `Object.assign()`: This method takes two or more objects as arguments and returns a new object containing all the enumerable own properties of those objects.
2. Spread operator (`...`): This operator creates a new object with the same keys as another object, and then copies the values from the original object into the new object.
3. Custom `assign()` function: This is a custom implementation that merges two objects using a loop.

**Pros and Cons**

Here are some pros and cons of each approach:

1. `Object.assign()`:
	* Pros: Simple to implement, widely supported by browsers and Node.js.
	* Cons: Can be slow due to its iterative nature, may not perform well with large datasets.
2. Spread operator (`...`):
	* Pros: Fast, efficient, and easy to read.
	* Cons: Limited support in older browsers and Node.js versions ( prior to ES6).
3. Custom `assign()` function:
	* Pros: Can be optimized for performance, may handle edge cases better than the other two approaches.
	* Cons: More complex to implement, requires more memory and CPU cycles.

**Library Usage**

None of the three approaches use any external libraries or dependencies.

**Special JS Features**

The benchmark uses the spread operator (`...`), which is a new feature introduced in ECMAScript 2018. The custom `assign()` function also uses JavaScript's built-in `for...in` loop, but does not rely on any special features beyond that.

**Other Considerations**

When choosing an approach, consider the following factors:

* Performance: Spread operator and custom `assign()` function are generally faster than `Object.assign()`.
* Compatibility: If you need to support older browsers or Node.js versions, use `Object.assign()` instead.
* Readability: Spread operator is often easier to read and understand, while `Object.assign()` may be more verbose.

**Alternatives**

If you're looking for alternatives, consider:

1. Lodash's `assignIn()` function, which provides a fast and efficient way to merge objects.
2. The `merge()` function from the `lodash` library, which also offers performance benefits over `Object.assign()`.
3. Custom implementation using JavaScript's built-in methods, such as `reduce()` or `forEach()`, but this may not be as efficient or readable as the other options.

Keep in mind that these alternatives are often more complex and harder to read than the original approaches, so use them with caution.

Related benchmarks:

Object.assign vs spread vs custom assign (version: 0)

Comparing performance of: Object.assign vs spread operator vs custom assign

Created: 4 years ago by: Guest

Jump to the latest result

Object.assign

spread operator

custom 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):