Benchmark: Object.assign vs direct assignment Mutation

Script Preparation code:

var data = {};

Tests:

Direct Assignment
for(var i = 0; i < 10000; i++) { data[`prop_${i}`] = true; }
Object.assign
let obj = {} for(var i = 0; i < 10000; i++) { var propName = `prop_${i}`; obj[propName]=true; } Object.assign(data, obj);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Direct Assignment
Object.assign

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 tested?**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for assigning properties to an object: direct assignment and using the `Object.assign()` method.

**Direct Assignment vs Object.assign()**

In the first test case, "Direct Assignment", the benchmark creates an empty object `data` and then assigns 10,000 properties to it using the dot notation (`data[`prop_${i}`] = true;`). This approach is simple and efficient, but may have limitations depending on the JavaScript engine or browser being used.

In the second test case, "Object.assign()", the benchmark creates an empty object `obj` and then assigns 10,000 properties to it using the dot notation (`var propName = 'prop_${i}'; obj[propName] = true;`). After that, it uses the `Object.assign()` method to assign all properties from `obj` to `data`. This approach involves creating a temporary object and copying its properties to another object.

**Pros and Cons**

- **Direct Assignment**
  - Pros:
    - Simple and efficient.
    - Does not require creating an extra object.
  - Cons:
    - May have issues with property names containing special characters or being too long, as they need to be quoted.
    - May have performance issues due to the large number of assignments.

- **Object.assign()**
  - Pros:
    - Can handle large numbers of properties and special character-containing property names.
    - Reduces memory usage by avoiding the creation of an extra object.
  - Cons:
    - Creates a temporary object, which can be slower for large datasets.
    - May not be supported in older browsers or JavaScript engines.

**Other Considerations**

- Both approaches have limitations when dealing with very large datasets or complex property names. The benchmark may not accurately represent real-world scenarios where property names might contain special characters or be too long.
- The use of `Object.assign()` assumes that the browser supports this method, which is a modern JavaScript feature.

**Library and Special JS Features**

Neither test case uses any external libraries. However, it does utilize some standard JavaScript features:

- The use of template literals (`${i}`) for generating property names in both approaches.
- The `Object.assign()` method itself.

The benchmark does not involve any special JavaScript features that are not part of the language's core syntax.

**Other Alternatives**

If you're looking to compare other assignment methods, you might consider using:

- Array methods like `Array.prototype.forEach()` or `Array.prototype.map()`
- Libraries like Lodash (`_.assign()`)
- Esoteric techniques like using a recursive function to create an object

Keep in mind that the choice of alternative depends on your specific requirements and use case.

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/104.0.0.0 Safari/537.36

Browser/OS: Chrome 104 on Windows

View result in a separate tab

Test name	Executions per second
Direct Assignment	585.1 Ops/sec
Object.assign	240.0 Ops/sec

Related benchmarks:

Object.assign vs direct assignment Mutation (version: 0)

Comparing performance of: Direct Assignment vs Object.assign

Created: 3 years ago by: Guest

Jump to the latest result

Direct Assignment

Object.assign

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):