Benchmark: frozen VS unfrozen object iteration times

Script Preparation code:

var o1 = {a: 1};
var o2 = {a: 1};

Object.freeze(o2);

Tests:

unfrozen iteration
for(var key in o1);
frozen iteration
for(var key in o2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
unfrozen iteration
frozen iteration

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.2 Safari/605.1.15

Browser/OS: Safari 26 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
unfrozen iteration	98646272.0 Ops/sec
frozen iteration	9072917.0 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 explain what's being tested, compared, and its pros and cons.

**What is being tested?**

The benchmark compares the iteration times of two objects: `o1` (unfrozen) and `o2` (frozen). The test checks how fast each object can be iterated over using a simple `for...in` loop.

**Options compared:**

There are two options being compared:

1. **Unfrozen object iteration**: This option uses the original, unfrozen `o1` object.
2. **Frozen object iteration**: This option uses the frozen `o2` object.

**Pros and Cons of each approach:**

* **Unfrozen object iteration**:
	+ Pros: Faster iteration times since the object is not frozen, allowing for more efficient internal workings.
	+ Cons: May be slower due to additional checks or overhead when iterating over an unfrozen object.
* **Frozen object iteration**:
	+ Pros: More predictable and consistent behavior, as the object's internal state is stabilized.
	+ Cons: Slower iteration times since the frozen object has additional overhead for stabilization.

**Library used (if any):**

None of the test cases use any external libraries. The benchmark only relies on standard JavaScript features and built-in objects like `Object.freeze()`.

**Special JS feature or syntax:**

The test case uses the `Object.freeze()` method to freeze the `o2` object, which is a JavaScript-specific feature for stabilizing an object's internal state.

**Other alternatives:**

In theory, other approaches could be used to iterate over objects, such as:

* Using `for...of` loops instead of `for...in` loops.
* Utilizing libraries like Lodash or Ramda that provide optimized iteration functions.
* Implementing custom iteration logic using recursive functions or other techniques.

However, the standard `for...in` loop is a common and widely supported approach in JavaScript, making it a suitable choice for this benchmark.

Now you know what's being tested and compared in this benchmark!

Related benchmarks:

frozen VS unfrozen object iteration times (version: 0)

Comparing performance of: unfrozen iteration vs frozen iteration

Created: 2 years ago by: Guest

Jump to the latest result

unfrozen iteration

frozen iteration

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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