Benchmark: Test for vs for in

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for loop
for(let i = 0; i<10000; i++){ for(let j = 0; j<obj.length; i++){ console.log(obj); } }
For in loop
for(let i = 0; i<10000; i++){ for(let key in obj){ console.log(obj); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for loop
For in loop

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data for MeasureThat.net, which represents a JavaScript microbenchmark.

**Benchmark Definition**

The benchmark definition is a JSON object that contains metadata about the test case. The relevant information here includes:

* `Name`: The name of the benchmark.
* `Description`: A brief description of the test case (empty in this example).
* `Script Preparation Code` and `Html Preparation Code`: These are used to prepare the JavaScript environment for the test case. In this case, the script preparation code defines a simple object `obj` with multiple properties.

**Individual Test Cases**

The benchmark consists of two individual test cases:

1. **For loop**: This test case uses a traditional `for` loop to iterate over an array-like object (`obj`). The loop variable `i` is used as the outer loop index, and `j` is used as the inner loop index.
2. **For in loop**: This test case uses the `for...in` loop to iterate over the properties of the `obj` object. The loop variable `key` is used to access each property.

**Comparison**

The benchmark compares the performance of two different iteration approaches:

* Traditional `for` loop (test case "for loop")
* `for...in` loop (test case "For in loop")

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

1. **Traditional `for` loop**:
	* Pros: Generally more efficient, as it uses indexed loops instead of property iteration.
	* Cons: Can be less intuitive for array-like objects with many properties, especially if you need to access multiple properties in a single iteration.
2. **For...in** loop:
	* Pros: Allows easy access to multiple properties in a single iteration, making it suitable for iterating over object properties.
	* Cons: Can be slower due to the overhead of property iteration and potential issues with property ordering.

**Library**

There is no specific library mentioned in this benchmark definition. The `obj` object is defined using standard JavaScript syntax.

**Special JS Features or Syntax**

Neither test case uses any special JavaScript features or syntax beyond basic syntax (e.g., `let`, `const`, `for`, `in`).

**Other Alternatives**

If you wanted to add more iteration approaches to the benchmark, here are some alternatives:

* Array.prototype.forEach()
* Array.prototype.map()
* Reduce()

Keep in mind that these approaches might not be suitable for all use cases and may have different performance characteristics.

In conclusion, this benchmark compares two common iteration methods in JavaScript: traditional `for` loops and `for...in` loops. The results can help developers understand the trade-offs between these approaches and make informed decisions about which one to use depending on their specific requirements.

Related benchmarks:

Test for vs for in (version: 0)

Comparing performance of: for loop vs For in loop

Created: 5 years ago by: Guest

Jump to the latest result

for loop

For in loop

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):