Benchmark: JavaScript spread operator vs Using assignment

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world', a: 'a', b: 'b', c: 'c' } const secondObject = { moreData: 'foo bar', a: 'a', b: 'b', c: 'c' } const finalObject = { ...firstObject, ...secondObject };
Using assignment
const firstObject = { sampleData: 'Hello world', a: 'a', b: 'b', c: 'c' } const secondObject = { moreData: 'foo bar', a: 'a', b: 'b', c: 'c' } const finalObject = { ...secondObject, a: firstObject.a, };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using assignment

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 break down what is being tested in this benchmark.

The benchmark compares two approaches for merging objects in JavaScript: using the spread operator (`...`) and using assignment (`=`).

**What is being tested?**

In the first test case, `Using the spread operator`, a function creates an object `finalObject` by spreading the properties of another object `secondObject` into it. The second object also has some common properties with the first object `firstObject`. The function then merges these two objects to create `finalObject`.

In the second test case, `Using assignment`, a similar approach is used, but instead of using the spread operator, the function assigns each property of `secondObject` to `finalObject` individually.

**Options compared**

The benchmark compares two approaches:

1. **Spread Operator (`...`)**: This syntax was introduced in ECMAScript 2018 (ES2018) and allows objects to be spread into a new object.
2. **Assignment (`=`)**: This is the traditional way of assigning properties from one object to another.

**Pros and Cons**

* **Spread Operator**
	+ Pros:
		- More concise and expressive syntax
		- Can be faster since it avoids the need for explicit assignment statements
	+ Cons:
		- May not be supported in older browsers or environments that don't have ES2018 support
		- Can lead to unexpected behavior if not used carefully (e.g., with optional chaining)
* **Assignment**
	+ Pros:
		- Widely supported across different browsers and environments
		- Less prone to unexpected behavior
	+ Cons:
		- More verbose syntax
		- May be slower due to the need for explicit assignment statements

**Library usage**

There is no library mentioned in this benchmark. The tests only use built-in JavaScript features.

**Special JS feature or syntax**

The spread operator (`...`) was introduced as a new way of object spreading, but it's also related to **rest parameters**, which were introduced in ECMAScript 2015 (ES6). However, the benchmark does not explicitly test rest parameters.

**Other alternatives**

For merging objects, other approaches could include:

* Using `Object.assign()`
* Creating a new object and then assigning properties from one or both objects
* Using a library like Lodash's `merge` function

However, the spread operator approach is generally considered the most concise and efficient way of merging objects in modern JavaScript.

Related benchmarks:

JavaScript spread operator vs Using assignment (version: 0)

Comparing performance of: Using the spread operator vs Using assignment

Created: 7 years ago by: Guest

Jump to the latest result

Using the spread operator

Using assignment

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):