Benchmark: my Object.assign-vs-Spread

Tests:

Object.assign
const acc = {a : [2,1], b: [1,3], c: [12, 23], d: [5,6]}; const newValue = { e: [3,4]}; return Object.assign(acc, newValue);
spread operator
const acc = {a : [2,1], b: [1,3], c: [12, 23], d: [5,6]}; const newValue = { e: [3,4]}; return { ...acc, ...newValue };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36

Browser/OS: Chrome 73 on Mac OS X 10.14.4

View result in a separate tab

Test name	Executions per second
Object.assign	3673571.5 Ops/sec
spread operator	3359725.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark!

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for shallow object assignment: `Object.assign()` and the spread operator (`{ ...acc, ...newValue }`).

**Options Compared**

There are two test cases:

1. **`Object.assign()`**: This method is used to copy objects or arrays by specifying an existing target object and a source object or array.
2. **Spread Operator (`{ ...acc, ...newValue }`)**: This operator is used to create a new object with the properties of the `acc` object and add additional properties from the `newValue` object.

**Pros and Cons of Each Approach**

1. **`Object.assign()`**:
	* Pros:
		+ Simple and widely supported.
		+ Can be used with arbitrary objects, not just JavaScript objects.
	* Cons:
		+ May require careful handling of prototype chains, null, or undefined values.
		+ Can lead to unexpected behavior if the target object is modified during assignment.
2. **Spread Operator (`{ ...acc, ...newValue }`)**:
	* Pros:
		+ More concise and readable than `Object.assign()`.
		+ Simplifies shallow object assignments with minimal overhead.
	* Cons:
		+ Requires modern JavaScript environments (ECMAScript 2018+) to support the spread operator syntax.

**Library or Built-in Functionality**

Neither of the two approaches relies on any external libraries. Both are built-in JavaScript functions that can be used directly in most browsers and Node.js environments.

**Special JS Features or Syntax**

The benchmark uses modern JavaScript syntax (ECMAScript 2018+) to demonstrate the spread operator. This means that the benchmark will only run correctly in environments that support this feature. If you need to run this benchmark in older environments, you may need to use a transpiler like Babel.

**Other Alternatives**

If you're interested in alternative approaches for shallow object assignment, consider using libraries or utilities like:

1. **Lodash**: Provides the `assign` function, which is similar to `Object.assign()`.
2. **Immutable.js**: Offers an immutable data structure approach that can be used with shallow assignments.
3. **Object.assign() alternatives**: There are alternative implementations of `Object.assign()` available in some browsers or libraries, such as the polyfill provided by the `assign` function in Lodash.

However, for most use cases, the built-in `Object.assign()` and spread operator syntax are sufficient and recommended due to their simplicity, readability, and widespread support.

Related benchmarks:

my Object.assign-vs-Spread (version: 0)

Comparing performance of: Object.assign vs spread operator

Created: 5 years ago by: Guest

Jump to the latest result

Object.assign

spread operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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