Benchmark: foreach - MeasureThat.net

HTML Preparation code:

That

Script Preparation code:

var arr = [];
for(var i = 0; i < 100000;i++) {
	arr.push(i);
}

function dup(i) {
	return i * 2;
}

Tests:

forEeach
arr.forEach(function (item) { dup(item); })
for loop
for (var j = 0, len = arr.length; j < len; j++) { dup(arr[j]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEeach
for 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.

Measuring JavaScript performance is crucial for ensuring efficient and scalable code. The provided Benchmark Definition JSON represents two test cases, each measuring the performance of a different approach to iterate over an array in JavaScript.

**Benchmark Definitions:**

1. `arr.forEach(function (item) { dup(item); })`
This test case uses the built-in `Array.prototype.forEach` method to iterate over the `arr` array and execute the `dup` function for each item.
2. `for (var j = 0, len = arr.length; j < len; j++) { dup(arr[j]); }`

This test case uses a traditional `for` loop to iterate over the `arr` array and execute the `dup` function for each item.

**Options Compared:**

The two options being compared are:

* Using the built-in `Array.prototype.forEach` method
* Using a traditional `for` loop

**Pros and Cons of Each Approach:**

**Array.prototype.forEach:**

Pros:

* More concise and readable code
* Efficient implementation that uses a specialized engine for performance-critical workloads
* Automatic handling of array bounds checking

Cons:

* Can be slower than traditional loops in some cases due to overhead from the engine's optimization techniques
* Less control over iteration variables (e.g., `i` is not explicitly declared)

**Traditional `for` Loop:**

Pros:

* More control over iteration variables and loop logic
* Potential for better cache locality, which can improve performance

Cons:

* More verbose code that may be harder to read
* Requires manual bounds checking, which can introduce errors if not implemented correctly

**Special Consideration:**

The `dup` function multiplies its input by 2. This operation is simple and inexpensive, but its effect on performance is negligible compared to the iteration loop itself.

**Library Used:**

None explicitly mentioned in the Benchmark Definition JSON.

However, it's worth noting that the `Array.prototype.forEach` method relies on a specialized engine under the hood. If you're interested in exploring this further, you can look into the ECMAScript standard for Array.prototype.forEach (section 23.3.1) or consult browser documentation specific to the version being used.

**Other Alternatives:**

Other iteration methods available in JavaScript include:

* `Array.prototype.map()`: Similar to `forEach`, but returns a new array instead of modifying the original
* `Array.prototype.reduce()`: Applies a reduction function to each element in the array, accumulating a result
* Closures or arrow functions with explicit loops (e.g., using `for...of`)

Keep in mind that these alternatives may have different performance characteristics, readability trade-offs, and use cases compared to traditional `for` loops.

In conclusion, measuring the performance of JavaScript iteration methods can provide valuable insights into code optimization strategies. By understanding the pros and cons of each approach, developers can make informed decisions about which method to choose for specific projects.

Related benchmarks:

foreach (version: 0)

Comparing performance of: forEeach vs for loop

Created: 9 years ago by: Guest

Jump to the latest result

forEeach

for 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):