Benchmark: for in break vs object keys 100

Script Preparation code:

var testObj = {}
for (let i = 0; i < 10000; i++) {
  const randomString = Math.random().toString(36).substr(2, 5);
  testObj[randomString] = randomString;
}

Tests:

for in break
let output; for (const key in testObj) { output = testObj[key]; console.log(output); break; }
Object keys
let output; output = Object.values(testObj)[0]; console.log(output);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for in break
Object keys

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 3 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. A microbenchmark is a small, isolated piece of code that measures the performance of a specific aspect of JavaScript.

In this case, we have a benchmark defined by a JSON object that describes two test cases: "for in break" and "Object keys". The goal is to compare the execution time of these two approaches.

**Script Preparation Code**

The script preparation code is where the benchmark creates a random object with 10,000 properties. This object will be used to test both the "for in break" and "Object keys" approaches.

```javascript
var testObj = {};
for (let i = 0; i < 10000; i++) {
    const randomString = Math.random().toString(36).substr(2, 5);
    testObj[randomString] = randomString;
}
```

This code creates a large object with random property names. The `for in` loop will iterate over the properties of this object, while the "Object keys" approach uses the `Object.values()` method to access the first element.

**Test Cases**

We have two test cases:

1. **"for in break"`: This test case uses a traditional `for in` loop with the `break` statement to iterate over the properties of the `testObj` object.
2. **"Object keys"`: This test case uses the `Object.values()` method to access the first element of the `testObj` object.

**Options Compared**

The two approaches are compared in terms of their execution time.

**Pros and Cons of Each Approach**

1. **"for in break"`:
	* Pros:
		+ Easy to understand and implement.
		+ May be more efficient due to caching and loop unrolling.
	* Cons:
		+ Can be slower for large objects due to the need to iterate over all properties.
2. **"Object keys"`:
	* Pros:
		+ Faster for large objects since it only accesses a single element.
	* Cons:
		+ Less intuitive and may require more memory access.

**Library**

In this benchmark, there is no specific library being used besides the built-in `Math` and `String` functions. The `Object.keys()` method is not being used explicitly, but rather implicitly through the `Object.values()` method.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax being used in these test cases. They are standard vanilla JavaScript implementations.

**Other Alternatives**

If you wanted to optimize this benchmark further, you could consider:

1. **Using a more efficient data structure**: Instead of creating a large object with random properties, you could use an array or a Map.
2. **Caching intermediate results**: If the loop iterations are independent and do not depend on previous iterations, you can cache intermediate results to avoid redundant calculations.
3. **Minimizing memory allocations**: Avoiding frequent memory allocations by reusing arrays or objects instead of creating new ones each iteration.
4. **Profiling**: Use profiling tools like Chrome DevTools or Node.js Inspector to identify performance bottlenecks and optimize the code accordingly.

Keep in mind that optimization should be guided by specific performance requirements and profiling results, rather than just experimenting with different approaches.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.198 Safari/537.36

Browser/OS: Chrome 86 on Windows

View result in a separate tab

Test name	Executions per second
for in break	1133.1 Ops/sec
Object keys	410.7 Ops/sec

Related benchmarks:

for in break vs object keys 100 (version: 0)

Comparing performance of: for in break vs Object keys

Created: 3 years ago by: Guest

Jump to the latest result

for in break

Object keys

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 3 days ago):