Benchmark: for-in vs object.keys isEmpty

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

function isEmptyFor(obj) {
  for (var key in obj) {
    return false;
  }
  return true;
}

function isEmptyObject(obj) {
  return Object.keys(obj).length === 0;
}

Tests:

for-in
isEmptyFor(obj)
Object.keys
isEmptyObject(obj)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
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/124.0.0.0 Safari/537.36 OPR/110.0.0.0 (Edition Yx 05)

Browser/OS: Opera 110 on Windows

View result in a separate tab

Test name	Executions per second
for-in	8403156.0 Ops/sec
Object.keys	4494202.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Explanation**

The provided benchmark measures the performance difference between two approaches to check if an object is empty: using a `for-in` loop and using the `Object.keys()` method with conditional checks.

In the first test case, "for-in", the script uses a `for-in` loop to iterate over the object's keys. If any key exists, it returns `false`, indicating that the object is not empty. If no key exists after iterating over all keys, it returns `true`.

In the second test case, "Object.keys", the script uses the `Object.keys()` method to get an array of the object's keys and checks if its length is 0 using conditional checks.

**Options Compared**

Two options are compared in this benchmark:

1. **`for-in` loop**: Iterates over the object's keys using a traditional `for-in` loop.
2. **`Object.keys()` method with conditional checks**: Uses the `Object.keys()` method to get an array of the object's keys and checks if its length is 0.

**Pros and Cons**

### `for-in` Loop

Pros:

* Simple and intuitive implementation
* Can be efficient for small objects or when working with specific property names

Cons:

* Iterates over all properties, even if some are not enumerable or are deleted
* Can lead to performance issues on large objects due to unnecessary iterations

### `Object.keys()` Method with Conditional Checks

Pros:

* More concise and expressive implementation
* Directly checks the length of the keys array, avoiding unnecessary iterations

Cons:

* May incur a slight overhead due to the use of the `Object.keys()` method
* Requires careful handling of cases where the object has no own properties or undefined values in the array

**Library/Utility Used**

In this benchmark, the following library is used:

* `Object`: provides methods like `keys()` and `length`

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax mentioned in the provided code.

**Alternatives**

Other alternatives for checking if an object is empty include:

1. **Using a simple equality check**: `if (obj === {}) { ... }`
2. **Using a `forEach` loop**: `Array.prototype.forEach.call(obj, () => { ... });`
3. **Using a custom iterator**: `const iterator = obj[Symbol.iterator](); if (!iterator.next().done) { ... }`

However, these alternatives may not be as efficient or readable as the provided approaches, and the benchmark is primarily focused on comparing the performance of the two mentioned options.

Related benchmarks:

for-in vs object.keys isEmpty (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 5 years ago by: Guest

Jump to the latest result

for-in

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):