Benchmark: Compare spread operator in objects vs set the properties in the object directly

Script Preparation code:

var data = [
  {
    'key': 'Username',
    'value': 'Benutzername'
  },
  {
    'key': 'Password',
    'value': 'Passwort'
  },
  {
    'key': 'name',
    'value': 'Julious'
  },
  {
    'key': 'lastname',
    'value': 'Extremus'
  }
];

Tests:

Using the spread operator
const newData = data.reduce((acc, { key, value }) => ({ ...acc, [key]: value }), {});
Set the properties directly in the object
const newData = data.reduce((acc, row) => (acc[row.key] = row.value, acc), {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Set the properties directly in the object

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**What is being compared?**

The benchmark compares two approaches to update an object:

1. Using the spread operator (`...`) to create a new object and then assigning its properties to an existing object.
2. Setting the properties directly on the existing object using bracket notation (`[key] = value`).

**Options: Spread Operator vs Direct Property Assignment**

The pros of using the spread operator are:

* Readability: It can make the code more concise and easier to understand, as it clearly conveys the intent of creating a new object with merged properties.
* Maintainability: If you need to add or remove properties in the future, the spread operator makes it easy to do so without modifying the original object.

The cons are:

* Performance overhead: Creating a new object using the spread operator can be slower than setting properties directly on an existing object, especially for large datasets.
* Memory usage: The spread operator creates a new object, which requires additional memory allocation.

On the other hand, direct property assignment has the following pros:

* Performance: Setting properties directly on an existing object is generally faster and more efficient, as it doesn't require creating a new object.
* Memory usage: Direct property assignment does not allocate new memory for the updated object.

However, this approach can be less readable and maintainable than using the spread operator.

**Library used**

There is no explicit library mentioned in the benchmark definition or test cases. However, `Array.prototype.reduce()` is used to perform the update operation on the `data` array.

**Special JS feature or syntax**

The spread operator (`...`) was introduced in ECMAScript 2018 (ES2018) as a way to create new objects from existing ones and expand arrays into objects.

Other considerations:

* The benchmark measures the performance of both approaches, with the results indicating that direct property assignment is faster.
* The benchmark assumes that the input data is an array of objects, where each object has two properties: `key` and `value`.
* The test cases are designed to cover the basic use case of updating an object using both methods.

**Alternatives**

Other approaches to update an object include:

* Using a library like Lodash or Ramda, which provide functions for merging objects.
* Using a custom function to iterate over the properties of the input data and update the output object.
* Using a template literal with the `Object.assign()` method to create a new object.

In general, the choice of approach depends on the specific requirements of the project, such as performance, readability, and maintainability.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser/OS: Chrome 104 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	2175007.5 Ops/sec
Set the properties directly in the object	10368491.0 Ops/sec

Related benchmarks:

Compare spread operator in objects vs set the properties in the object directly (version: 0)

This benchmark is to compare the cost of using the spread operator in objects

Comparing performance of: Using the spread operator vs Set the properties directly in the object

Created: 5 years ago by: Registered User

Jump to the latest result

Using the spread operator

Set the properties directly in the object

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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