Benchmark: TestArrayAllocation

Script Preparation code:

var array = new Array(1000000).fill(0);

function getObj() {
 	return {x: 0, Y: 0}; 
}

Tests:

1
for (let i = 0; i < array.length; i++) array[i] = getObj();
2
for (let i = 0; i < array.length; ++i) array[i] = getObj();
3
const l = array.length; for (let i = 0; i < l; ++i) array[i] = getObj();
4
for (const i in array) array[i] = getObj();
5
let i; for (i in array) array[i] = getObj();
6
const arr2 = array.map(_ => getObj());
7
const arr3 = []; for (let i = 0; i < 1000000; i++) arr3.push(getObj());

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
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7

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided JSON benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is testing how quickly JavaScript arrays can be populated with objects using different methods.

**Options Compared**

There are six options compared:

1. **Traditional For Loop**: `for (let i = 0; i < array.length; i++) array[i] = getObj();`
2. **Incrementing Index Without Decrementation**: `for (let i = 0; i < array.length; ++i) array[i] = getObj();`
3. **Looping Through Array Indices Directly**: `const l = array.length; for (let i = 0; i < l; ++i) array[i] = getObj();`
4. **For-In Loop**: `for (const i in array) array[i] = getObj();`
5. **Variable Initialization Inside the Loop**: `let i; for (i in array) array[i] = getObj();`
6. **Array Method: map()**: `const arr2 = array.map(_ => getObj());`

**Pros and Cons of Each Approach**

1. **Traditional For Loop**: This is a straightforward approach, easy to understand and maintain. It's likely to be the most readable code for developers familiar with JavaScript.
	* Pros: Easy to read and understand.
	* Cons: May not be as efficient due to index calculations.
2. **Incrementing Index Without Decrementation**: This method avoids incrementing the index variable, which can lead to unnecessary reassignments of the `i` variable.
	* Pros: Reduces unnecessary reassignments of `i`.
	* Cons: Less readable than traditional for loops.
3. **Looping Through Array Indices Directly**: Using an index directly is a simple and efficient way to access array elements.
	* Pros: Efficient, easy to read.
	* Cons: May require more lines of code compared to traditional for loops.
4. **For-In Loop**: This method uses the `in` operator to loop through the array's own enumerable properties (not indices).
	* Pros: Shorter code, efficient.
	* Cons: Less readable than traditional for loops; may not work as expected with non-enumerable properties.
5. **Variable Initialization Inside the Loop**: Initializing a variable inside the loop can lead to unexpected behavior if the variable is reassigned or goes out of scope.
	* Pros: None significant in terms of performance.
	* Cons: Less readable, potentially error-prone.
6. **Array Method: map()**: Using `map()` applies a function to each element in an array and returns a new array with the results.
	* Pros: Efficient, concise.
	* Cons: May not be suitable for all use cases (e.g., if you need to modify the original array).

**Other Considerations**

* **Array Allocation**: Creating a large array can have performance implications due to memory allocation overhead.
* **Object Creation**: The `getObj()` function creates objects on each iteration, which may lead to additional memory allocations and garbage collection.

**Library Usage**

There is no explicit library mentioned in the provided benchmark definition or test cases. However, some libraries might be implicitly used, such as:

* `console` for logging output
* `Array.prototype.map()`, which is a part of the JavaScript standard library

**Special JS Features/Syntax**

None are explicitly mentioned in the provided information.

I hope this explanation helps!

Related benchmarks:

TestArrayAllocation (version: 0)

Comparing performance of: 1 vs 2 vs 3 vs 4 vs 5 vs 6 vs 7

Created: 3 years ago by: Guest

Jump to the latest result

1

2

3

4

5

6

7

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):