Benchmark: testtest54654 - MeasureThat.net

Script Preparation code:

var obj = Array.from({ length: 10000 }).map((value, i) => i).reduce((val, v) => { val[v] = v; return val; }, {})

Tests:

Entries
const result = {}; Object.entries(obj).forEach(([key ,value])=>{ result[key] = value })
For
const result = {} for (const key of Object.keys(obj)) { result[key] = obj[key] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Entries
For

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark, where users can create and run benchmarks on their own scripts. The benchmark in question compares two approaches for iterating over an object: `Object.entries()` and a traditional `for` loop using `Object.keys()`. We'll dive into each approach, its pros and cons, and discuss other considerations.

**Approach 1: Object.entries()**

```javascript
const result = {};
Object.entries(obj).forEach(([key, value]) => {
  result[key] = value;
});
```

This approach uses the `Object.entries()` method to get an array of key-value pairs from the `obj` object. The `forEach()` method is then used to iterate over this array and assign each value to a property in the `result` object.

Pros:

* Concise and readable code
* Easy to maintain, as it follows a standard pattern

Cons:

* Might be slower than traditional loops due to the overhead of creating an array and iterating over it

**Approach 2: Traditional For Loop**

```javascript
const result = {};
for (const key of Object.keys(obj)) {
  result[key] = obj[key];
}
```

This approach uses a traditional `for` loop with `Object.keys()` to iterate over the object's keys. The value is then assigned to the corresponding property in the `result` object.

Pros:

* Can be faster, as it avoids the overhead of creating an array
* Often preferred for performance-critical code

Cons:

* More verbose and harder to read compared to the `Object.entries()` approach
* Might lead to bugs if not carefully maintained (e.g., forgetting to update the loop variable)

**Library: Object.keys()**

The `Object.keys()` method is a built-in JavaScript function that returns an array of a given object's property names. It's used in both approaches above.

**Special JS Feature/ Syntax: None**

There are no special features or syntaxes being tested in this benchmark. The code is straightforward and follows standard JavaScript practices.

**Other Alternatives**

If you're interested in alternative approaches, here are some options:

* `for...in` loop: This loop iterates over the object's properties using their names as strings.
```javascript
const result = {};
for (const key in obj) {
  if (Object.prototype.hasOwnProperty.call(obj, key)) {
    result[key] = obj[key];
  }
}
```
* `reduce()` method with a custom callback: This approach uses the `reduce()` method to accumulate values from an array.
```javascript
const result = {};
Array.from({ length: 10000 }).map((value, i) => i).reduce((acc, v) => {
  acc[v] = value;
  return acc;
}, {});
```
Keep in mind that these alternatives might have different performance characteristics and are not necessarily better or worse than the approaches being compared.

In conclusion, the benchmark compares two common ways to iterate over an object in JavaScript: `Object.entries()` and a traditional `for` loop using `Object.keys()`. While the former is concise and readable, the latter can be faster due to its lack of overhead. Ultimately, the choice between these approaches depends on your specific use case and performance requirements.

Related benchmarks:

testtest54654 (version: 0)

Comparing performance of: Entries vs For

Created: 5 years ago by: Guest

Jump to the latest result

Entries

For

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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