Benchmark: property assign vs spread operator

Tests:

property assignment
var params = { b:"hello", c: true, d:7 }; for (var i = 0; i < 10000; i++) { params[i] = i; }
spread operator
var params = { b:"hello", c: true, d:7 }; for (var i = 0; i < 10000; i++) { params = { [i]: i, ...params}; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
property assignment
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark test case.

**Benchmark Name:** property assign vs spread operator
**Description:** This test compares the performance of two different methods for assigning properties to an object: direct assignment and using the spread operator.

**Test Cases:**

1. **property assignment**: In this test, a large array (10000 elements) is created, and each element is assigned to a corresponding property in the `params` object using a simple assignment (`params[i] = i;`).
2. **spread operator**: This test uses the spread operator (`...`) to create a new object with the same properties as `params`, but with an additional property `i` set to its value, where `i` is the loop variable.

**Benchmark Result:**

The latest benchmark result shows that:

* The **property assignment** method performs significantly better (7424.14 executions per second) than the **spread operator** method (0.11 executions per second).

**What's being tested?**

In this test, we're measuring the performance of two different approaches to assigning properties to an object:

1. **Direct Assignment**: Simply assigning values to an existing object using a simple assignment (`params[i] = i;`).
2. **Spread Operator**: Using the spread operator (`...`) to create a new object with additional properties.

**What are the pros and cons of each approach?**

1. **Direct Assignment**:
	* Pros: Fast, efficient, and widely supported.
	* Cons: None significant in this test case.
2. **Spread Operator**:
	* Pros: Can be useful for creating new objects with existing properties and adding additional ones.
	* Cons: Significantly slower than direct assignment in this test case.

**Other considerations:**

1. **Object Size**: The size of the object being assigned to can affect performance.
2. **Loop Complexity**: The complexity of the loop (e.g., nested loops) can impact performance.
3. **Browser/Engine**: The performance difference between browsers and JavaScript engines may vary.

**What library is used?**

None in this test case.

**Special JS feature or syntax?**

The spread operator (`...`) is a special JavaScript feature introduced in ES6 (ECMAScript 2015).

**Alternatives:**

1. **Object.assign()**: A method that can be used to assign properties from one object to another.
2. **lodash.assign()**: A utility function from the Lodash library that assigns properties from one object to another.

Note that these alternatives may have their own performance implications and use cases, which are not explored in this specific test case.

Related benchmarks:

property assign vs spread operator (version: 0)

Comparing performance of: property assignment vs spread operator

Created: 6 years ago by: Guest

Jump to the latest result

property assignment

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):