Benchmark: Object filter mappingv2

Script Preparation code:

function makeid() {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (var i = 0; i < 5; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));

  return text;
}

window.parentObj = {};

for (let i = 0; i < 100; i++) {
	window.parentObj[makeid()] = makeid();
}

Tests:

object.entries
const entries = Object.entries(window.parentObj).filter(([k, v], i) => ((i % 2) === 0)); if(entries.length > 0) Object.fromEntries(entries);
object.keys
const keys = Object.keys(window.parentObj).reduce((acc, k, i) => { if ((i % 2) === 0) { acc[k] = window.parentObj[k]; } return acc }, {}); if(Object.keys(keys).length > 0) true;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
object.entries
object.keys

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser/OS: Chrome 125 on Windows

View result in a separate tab

Test name	Executions per second
object.entries	104901.9 Ops/sec
object.keys	169235.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its components.

**Benchmark Definition**

The benchmark is called "Object filter mappingv2" and it compares the performance of two approaches to create a new object by filtering out entries from an existing object: `Object.fromEntries` and `Object.keys.reduce`.

**Approaches Compared**

There are two main approaches being compared:

1. **`Object.entries`**: This approach uses the `entries()` method to get an array of key-value pairs from the object, filters out every other entry using a callback function, and then uses `Object.fromEntries` to create a new object from the filtered entries.
2. **`Object.keys.reduce`**: This approach uses the `keys()` method to get an array of keys from the object, reduces it to a new object using a callback function, and filters out every other entry.

**Pros and Cons**

1. **`Object.entries`**:
	* Pros: concise and readable code.
	* Cons: might be slower due to the overhead of creating an array from key-value pairs.
2. **`Object.keys.reduce`**:
	* Pros: can be more efficient if the object is large, as it avoids creating an array.
	* Cons: might be less readable due to the use of `reduce`.

**Library and Special JS Features**

There are no external libraries used in this benchmark.

**Special JS Features (Not Applicable)**

None of the test cases use any special JavaScript features or syntax that would require additional explanation.

**Other Considerations**

The benchmark uses a custom object `window.parentObj` to create entries for the filter operation. This object is populated with random keys and values before running the benchmark.

**Alternative Approaches**

There are other ways to achieve the same result as the benchmark:

1. **Using `Object.fromEntries` with an array comprehension**: `const filteredEntries = Object.entries(window.parentObj).filter(([k, v], i) => (i % 2 === 0)); const result = Object.fromEntries(filteredEntries);`
2. **Using `Array.prototype.filter()` on the key-value pairs**: `const keys = Object.keys(window.parentObj).map(k => [k, window.parentObj[k]]); const filteredKeys = keys.filter(([k, v], i) => (i % 2 === 0)); const result = Object.fromEntries(filteredKeys.map(([k, v]) => [k, v]));`

These alternative approaches might have different performance characteristics and are not included in the benchmark.

Related benchmarks:

Object filter mappingv2 (version: 0)

benchmark comparing the perf of creating a new object by filter out entries

Comparing performance of: object.entries vs object.keys

Created: one year ago by: Guest

Jump to the latest result

object.entries

object.keys

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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