Benchmark: Increment array with for( ... Object.Entries(...) ) vs Object.Entries(...).reduce

Script Preparation code:

var hashmap = {
      id1: {
        id: 'id1',
        content: ''
      },
      id2: {
        id: 'id2',
        content: ''
      },
      id3: {
        id: 'id3',
        content: ''
      }
 };

Tests:

for
const newhashmap = {} for (const [key, value] of Object.entries(hashmap)) { newhashmap[key] = value; }
reduce
const newhashmap = Object.entries(hashmap).reduce((acc, [key, value]) => { const _acc = {...acc}; _acc[key] = value; return _acc }, {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
reduce

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its various aspects.

**Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. A microbenchmark is a small test designed to measure the performance of a specific part of code. In this case, we're analyzing two approaches to incrementing an array: using a traditional `for` loop with `Object.entries()` versus using the `reduce()` method.

**Test Case 1: "for"**

The first test case uses a traditional `for` loop with `Object.entries()`. Here's what's happening:

* `Object.entries(hashmap)` returns an array of key-value pairs from the `hashmap` object.
* The `for` loop iterates over this array, assigning each key-value pair to variables `key` and `value`.
* Inside the loop, a new property is added to the `newhashmap` object using `newhashmap[key] = value;`.

**Pros of traditional "for" approach:**

1. **Control**: The developer has more control over the iteration process.
2. **Familiarity**: This syntax is commonly used in JavaScript development.

**Cons of traditional "for" approach:**

1. **Performance**: This approach can be slower than `reduce()` because it involves an additional loop for assigning values to the new object.
2. **Code duplication**: If there's a need to perform similar operations on multiple objects, this syntax would require duplicated code.

**Test Case 2: "reduce"**

The second test case uses the `reduce()` method to increment the array:

* `Object.entries(hashmap)` returns an array of key-value pairs.
* The `reduce()` method applies a callback function to each element in the array, reducing it to a single value (in this case, a new object).
* Inside the callback function, a property is added to the accumulator object (`acc`) using `acc[key] = value;`.

**Pros of "reduce" approach:**

1. **Performance**: This approach can be faster than the traditional `for` loop because it's optimized for array iteration.
2. **Conciseness**: The code is more compact and easier to read.

**Cons of "reduce" approach:**

1. **Complexity**: The developer needs to understand the implications of using `reduce()` on object creation.
2. **Less control**: The developer has less control over the iteration process compared to traditional loops.

**Library Used**

There is no specific library used in this benchmark, as it's a basic demonstration of two different approaches to incrementing an array.

**Special JavaScript Features or Syntax**

None are mentioned in the provided code snippets. However, note that `Object.entries()` and `reduce()` are part of the ECMAScript standard since ES6, so this benchmark takes advantage of modern JavaScript features.

**Alternative Approaches**

Other alternatives for incrementing an array include:

1. **Array.prototype.forEach()**: Similar to traditional loops but uses a more concise syntax.
2. **Array.prototype.map()`: Creates a new array with transformed values (e.g., adding a property).
3. **Array.prototype.fill()**: Fills a specified value into an array.
4. **Destructuring assignment**: Assigns multiple values from an object to variables in a single statement.

Keep in mind that the best approach depends on the specific use case and performance requirements of your project.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36

Browser/OS: Chrome 76 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
for	1572057.9 Ops/sec
reduce	1494075.6 Ops/sec

Related benchmarks:

Increment array with for( ... Object.Entries(...) ) vs Object.Entries(...).reduce (version: 0)

Comparing performance of: for vs reduce

Created: 5 years ago by: Guest

Jump to the latest result

for

reduce

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):