Benchmark: 2022.07.30 assign vs spread

Tests:

Object.assign mutate
var params = { b:"hello", c: true, d:7 }; var p = { a: 2 } var other = Object.assign(p, params);
spread operator
var params = { b:"hello", c: true, d:7 }; var p = { a: 2 } var other = { ...params, ...p };
Manual Update
var params = { b:"hello", c: true, d:7 }; var p = {a: 2, b: "NEW"} for (const key of Object.keys(p)) { params[key] = p[key] }
object assign copy
var params = { b:"hello", c: true, d:7 }; var p = { a: 2 } var other = Object.assign({}, params, p);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign mutate
spread operator
Manual Update
object assign copy

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36

Browser/OS: Chrome 103 on Windows

View result in a separate tab

Test name	Executions per second
Object.assign mutate	5276332.0 Ops/sec
spread operator	2355044.5 Ops/sec
Manual Update	4714862.0 Ops/sec
object assign copy	4797114.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what's being tested.

**Benchmark Definition**

The JSON data defines a JavaScript benchmark that compares different approaches to update an object. The script is designed to create two objects, `params` and `p`, with some common properties, and then apply one of three updates to `params`:

1. **Object.assign mutate**: Directly modifies the `params` object by passing it as the first argument to `Object.assign`.
2. **Spread operator**: Uses the spread operator (`{ ...params, ...p }`) to create a new object that combines the properties of `params` and `p`.
3. **Manual Update**: Loops over the keys of `p` and manually updates the corresponding properties in `params`.

**Options Compared**

The benchmark compares the performance of these three approaches:

*   **Object.assign mutate**: A simple, straightforward approach that modifies the original object.
*   **Spread operator**: A more modern and efficient approach that creates a new object without modifying the original.
*   **Manual Update**: An older approach that loops over the keys to update the properties.

**Pros and Cons**

Here's a brief summary of each approach:

*   **Object.assign mutate**:
    *   Pros: Simple, easy to understand.
    *   Cons: Can be slower due to the overhead of modifying the original object.
*   **Spread operator**:
    *   Pros: More efficient, creates a new object without modifying the original.
    *   Cons: May require more understanding of modern JavaScript features.
*   **Manual Update**:
    *   Pros: Suitable for older browsers or environments that don't support the spread operator.
    *   Cons: Can be slower and less readable due to the loop.

**Library Usage**

None of the provided benchmarks use any external libraries. They are self-contained, only requiring JavaScript as a dependency.

**Special JS Features/Syntax**

The benchmark uses modern JavaScript features like:

*   Spread operator (`{ ...params, ...p }`)
*   Object.assign() function
*   Loops and iterations

These features are widely supported by modern browsers, but may not work in older environments or with specific browser versions.

**Alternative Approaches**

Other alternatives to consider for updating objects include:

*   Using the `Object.keys()` method to iterate over keys:
    ```javascript
for (const key of Object.keys(p)) {
  params[key] = p[key];
}
```
*   Using the `for...in` loop instead of `for...of` for iterating over properties:
    ```javascript
for (let key in p) {
  params[key] = p[key];
}
```
*   Using a library like Lodash to simplify object updates (`_.assign()`, `_merge()`)

Keep in mind that the performance benefits of these alternatives may be similar or inferior to the spread operator approach, depending on the specific use case and browser environment.

Related benchmarks:

2022.07.30 assign vs spread (version: 0)

Comparing performance of: Object.assign mutate vs spread operator vs Manual Update vs object assign copy

Created: 2 years ago by: Guest

Jump to the latest result

Object.assign mutate

spread operator

Manual Update

object assign copy

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):