Benchmark: Object.keys.length vs sum

Script Preparation code:

window.obj = {};

for (var i = 0, len = 100; i < len; i++) {
  obj['key' + i] = 'value' + i;
}

Tests:

_.isEmpty
let len = 0; for (const key in obj) { if (obj.hasOwnProperty(key)) { len++; break; } }
Object.keys().length
let len = Object.keys(window.obj).length;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
_.isEmpty
Object.keys().length

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36

Browser/OS: Chrome 106 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
_.isEmpty	694576.4 Ops/sec
Object.keys().length	691077.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The benchmark compares two approaches to get the length of an object's keys in JavaScript:

1. Using `for...in` loop with `hasOwnProperty()`
2. Using `Object.keys()` method

The benchmark uses a simple script preparation code to create a test object with 100 properties, and then executes both test cases.

**Script Preparation Code**

```javascript
window.obj = {};
for (var i = 0, len = 100; i < len; i++) {
  obj['key' + i] = 'value' + i;
}
```

This code creates an object `obj` with 100 properties and assigns a simple string value to each property.

**Html Preparation Code**

There is no HTML preparation code provided, which means that the benchmark only runs in a Node.js environment or a browser console.

**Test Cases**

The benchmark consists of two test cases:

1. **_.isEmpty** (using `for...in` loop with `hasOwnProperty()`)

```javascript
let len = 0;
for (const key in obj) {
  if (obj.hasOwnProperty(key)) {
    len++;
    break;
  }
}
```

This test case uses a `for...in` loop to iterate over the object's properties and increments a counter (`len`) when it finds a property that exists.

2. **Object.keys().length** (using `Object.keys()` method)

```javascript
let len = Object.keys(window.obj).length;
```

This test case simply uses the `Object.keys()` method to get an array of the object's properties and then returns its length (`len`).

**Library Used**

None, as this benchmark only uses built-in JavaScript features.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax used in these benchmarks. They use standard JavaScript syntax and features available in most browsers and Node.js environments.

**Pros and Cons of Different Approaches**

1. **Using `for...in` loop with `hasOwnProperty()`**
	* Pros:
		+ Can handle objects with inherited properties
		+ Can be more efficient than using `Object.keys()`
	* Cons:
		+ Can be slower due to the overhead of the loop and the `hasOwnProperty()` check
2. **Using `Object.keys()` method**
	* Pros:
		+ Faster than using a loop, as it returns an array of keys
	* Cons:
		+ May not work correctly on older browsers or environments that don't support `Object.keys()`

**Other Alternatives**

1. **Array.prototype.map()**: Instead of using a loop, you can use `Array.prototype.map()` to create a new array with the object's properties as strings.
```javascript
let len = Array.from(window.obj).length;
```
This approach is faster than using a loop, but may not work correctly on older browsers or environments that don't support `Array.prototype.map()`.
2. **Object.entries()**: Another alternative to `Object.keys()` is `Object.entries()`, which returns an array of key-value pairs.
```javascript
let len = Object.entries(window.obj).length;
```
This approach may be faster than using `Object.keys()`, but may not work correctly on older browsers or environments that don't support `Object.entries()`.

Related benchmarks:

Object.keys.length vs sum (version: 0)

Comparing performance of: _.isEmpty vs Object.keys().length

Created: 2 years ago by: Guest

Jump to the latest result

_.isEmpty

Object.keys().length

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):