Benchmark: check obj empty state with for-in vs object.keys

Script Preparation code:

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

Tests:

for-in
withFor()
Object.keys
withObjKeys()

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:

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

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Let's dive into the benchmark and explain what's being tested.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that compares two approaches to check if an object is empty: using `for-in` loop and using the `Object.keys()` method.

**Options Compared**

Two options are compared:

1. **withFor()**: This function uses a `for-in` loop to iterate over the object's properties. The loop returns `true` as soon as it encounters a property (i.e., any non-empty value), and `false` if no properties are found.
2. **withObjKeys()**: This function uses the `Object.keys()` method to get an array of the object's property names. It then checks if the array has a length of 0, which indicates an empty object.

**Pros and Cons**

Here's a brief summary of each approach:

* **withFor():**
	+ Pros: Can be faster for small objects with many properties because it returns as soon as it finds a non-empty value.
	+ Cons: May perform unnecessary iterations if the object is large or has many empty properties. Additionally, this approach can lead to issues if the object's property names are not unique (e.g., when `a` and `b` both have the same value).
* **withObjKeys():**
	+ Pros: More predictable behavior, as it always checks the entire array of property names before returning.
	+ Cons: May be slower for large objects due to the overhead of creating and iterating over the array.

**Library Used**

The benchmark uses the `Object.keys()` method, which is a part of the JavaScript Standard Library. This method returns an array of strings containing the property names of the given object. The purpose of this library is to provide a convenient way to iterate over an object's properties and perform various operations on them.

**Special JS Feature/Syntax**

There is no special JavaScript feature or syntax being tested in this benchmark. However, it's worth noting that `for-in` loops can be affected by the behavior of object property names, such as when using getters or setters.

**Other Alternatives**

If you need to check if an object is empty, here are some alternative approaches:

* Using `Object.keys()` and checking its length directly: `Object.keys(obj).length === 0`
* Using a simple `in` operator with the `hasOwnProperty()` method: `for (var key in obj) { if (!obj.hasOwnProperty(key)) break; }`
* Using the `Map` data structure to store object properties as keys and then checking its size: `const map = new Map(Object.entries(obj)); return map.size === 0`

Keep in mind that these alternatives may have different performance characteristics compared to the original `withFor()` and `withObjKeys()` approaches.

Related benchmarks:

check obj empty state with for-in vs object.keys (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 4 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

No previous run results

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