Benchmark: For vs Foreach - MeasureThat.net

Script Preparation code:

var test = [
    { name: 'John', age: 75 },
    { name: 'Mike',    age: 85 },
    { name: 'Jane',   age: 95 },
    { name: 'June', age: 65 },
    { name: 'Mick',       age: 55 }
];

Tests:

for
for (var i = 0; i < test.length; i++) { console.log(test[i]); }
foreach
test.forEach(function(test, index) { console.log(test); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark.

**What is being tested?**

The provided benchmark tests two approaches to iterate over an array: traditional `for` loop and `forEach` method. The test case generates an array of objects, each representing a person with a name and age, and measures the performance difference between these two iteration methods.

**Options compared:**

1. **Traditional `for` loop**: This approach uses a manual index variable to iterate over the array elements.
2. **`forEach` method**: This is a built-in JavaScript method that executes a provided callback function for each element in an array.

**Pros and Cons of each approach:**

1. **Traditional `for` loop**:
	* Pros:
		+ More control over iteration variables and bounds.
		+ Can be faster due to reduced overhead of function calls.
	* Cons:
		+ Requires manual management of index variable.
		+ Less readable code compared to `forEach`.
2. **`forEach` method**:
	* Pros:
		+ Concise and readable code.
		+ Reduced overhead due to built-in function call.
	* Cons:
		+ Less control over iteration variables and bounds.
		+ May be slower than traditional `for` loop due to additional overhead.

**Library used:**

None explicitly mentioned, but the `forEach` method is a built-in JavaScript API. However, it's worth noting that some browsers may have slightly different implementations or optimizations for this method.

**Special JS feature or syntax:**

The benchmark uses no special features or syntax other than the standard JavaScript `for`, `forEach`, and array methods.

**Other alternatives:**

For iterating over arrays in JavaScript, you might also consider:

1. **`reduce()` method**: While not primarily designed for iteration, it can be used to process arrays by accumulating values.
2. **Arrow functions and spread operators**: These can provide concise ways to define small functions, but may not offer performance advantages over traditional loops or `forEach`.
3. **Loops with incrementing index variables**: This approach would involve using a different variable name for the loop counter, which might be more readable than manual indexing.

In summary, the benchmark compares two common approaches to iterate over arrays in JavaScript: traditional `for` loop and `forEach` method. The choice between these approaches depends on your specific use case, code readability requirements, and performance concerns.

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36

Browser/OS: Chrome 86 on Linux

View result in a separate tab

Test name	Executions per second
for	7632.1 Ops/sec
foreach	8337.4 Ops/sec

Related benchmarks:

For vs Foreach (version: 0)

Testing performance

Comparing performance of: for vs foreach

Created: 7 years ago by: Guest

Jump to the latest result

for

foreach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):