Benchmark: forin vs obj.values().map

Script Preparation code:

var obj = {
  'a': {
    id: 'a',
    num: 1
  },
  'b': {
    id: 'b',
    num: 1
  },
  'c': {
    id: 'c',
    num: 1
  },
  'd': {
    id: 'd',
    num: 1
  },
  'e': {
    id: 'e',
    num: 1
  },
  'f': {
    id: 'f',
    num: 1
  },
  'g': {
    id: 'g',
    num: 1
  },
};

Tests:

for in
for (var key in obj) { console.log(obj[key].id); }
obj.values.map
Object.values(obj).map((item) => { console.log(item.id) })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for in
obj.values.map

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition and Script Preparation Code**

The provided JSON represents a benchmark definition, which is a test case for comparing two approaches: `for...in` and `obj.values().map`. The script preparation code provides an object `obj` with multiple properties (keys) that contain objects as values. This setup allows the tests to focus on the iteration over these nested objects.

**Options Compared**

The benchmark compares two options:

1. **For loop with `for...in`**: Iterates over the keys of the outer object (`obj`) and, for each key, logs the value of the corresponding property in the inner object.
2. **`Object.values()` followed by `.map()`**: Iterates over an array containing the values of all properties in the object using `Object.values()`, and then applies a transformation function to each element using `.map()`, logging the result.

**Pros and Cons**

### For loop with `for...in`

Pros:

* Well-established, widely supported syntax.
* Can be optimized by the JavaScript engine for iteration.

Cons:

* May lead to slower performance due to extra iterations or overhead.

### Object.values() followed by .map()

Pros:

* Can provide a more efficient and concise way of accessing object values.
* Allows for easy transformation of data using the `.map()` method.

Cons:

* May incur additional overhead due to array creation, iteration, and function call.

**Library Used**

None. The `Object.values()` and `.map()` methods are built-in JavaScript functions.

**Special JS Feature or Syntax**

None mentioned in the provided JSON.

**Other Considerations**

When choosing between these approaches, consider the following factors:

* **Readability**: For loop with `for...in` might be more readable for some developers, while `Object.values()` followed by `.map()` can provide a more concise and expressive way of accessing data.
* **Performance**: The benchmark results may vary depending on the JavaScript engine, hardware, and other factors. As shown in the latest benchmark result, `Object.values().map()` seems to be slightly faster.
* **Maintenance**: For loop with `for...in` might require additional code for handling edge cases (e.g., objects without keys), while `Object.values()` followed by `.map()` is more straightforward.

**Alternative Approaches**

Other alternatives for accessing and manipulating object data include:

1. **Using array methods like `forEach()`**, which can provide similar functionality to `for...in` but with a more modern syntax.
2. **Using arrow functions** within the `Object.values()` method, which can simplify the transformation logic.
3. **Using other libraries or modules**, such as Lodash, that offer additional utility functions for working with objects and arrays.

Keep in mind that these alternatives may introduce trade-offs in terms of readability, performance, or compatibility, depending on your specific use case and requirements.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36

Browser/OS: Chrome 111 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for in	26119.6 Ops/sec
obj.values.map	27410.5 Ops/sec

Related benchmarks:

forin vs obj.values().map (version: 0)

Comparing performance of: for in vs obj.values.map

Created: one year ago by: Guest

Jump to the latest result

for in

obj.values.map

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):