Benchmark: .length vs var randomized Arrays

Script Preparation code:

for (var a=[],i=0;i<100;++i) a[i]=i;

// http://stackoverflow.com/questions/962802#962890
function shuffle(array) {
  var tmp, current, top = array.length;
  if(top) while(--top) {
    current = Math.floor(Math.random() * (top + 1));
    tmp = array[current];
    array[current] = array[top];
    array[top] = tmp;
  }
  return array;
}

var p = shuffle(a);

Tests:

no var
console.log(p.length);
var
var l = p.length; console.log(l);
const
const l = p.length; console.log(l);
accessing .length x 10
console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length);
storing and accessing variable x 10
const l = p.length; console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
no var
var
const
accessing .length x 10
storing and accessing variable x 10

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 dive into the explanation of the provided benchmark.

**Benchmark Definition**
The benchmark is designed to compare the performance of accessing the `length` property of an array using three different approaches: no `var`, with `var`, and with `const`. The benchmark creates a randomized array of 100 elements, shuffles it, and then measures the time taken to access the length of the array using each approach.

**Options compared**

1. **No `var`**: This option uses the built-in array property `length` directly, without declaring a variable.
2. **With `var`**: This option declares a variable `l` and assigns the value of `p.length` to it before logging it to the console.
3. **With `const`**: This option also declares a variable `l`, but uses the `const` keyword to declare it, which means its value cannot be reassigned.

**Pros and Cons**

1. **No `var`**:
	* Pros: Direct access to the array property without introducing extra variables.
	* Cons: May not be as readable or maintainable for complex calculations.
2. **With `var`**:
	* Pros: Easy to understand and maintain, especially for simple calculations.
	* Cons: Assigns the value of `p.length` to a variable before logging it, which can lead to unnecessary computations.
3. **With `const`**:
	* Pros: Ensures that the variable is not reassigned, making it more predictable.
	* Cons: May be less readable or maintainable for complex calculations due to the extra variable declaration.

**Library and its purpose**
The benchmark uses a custom `shuffle` function from Stack Overflow (https://stackoverflow.com/questions/962802#962890) to generate a randomized array. The purpose of this library is to provide a simple way to shuffle an array in JavaScript.

**Special JS feature or syntax**
The benchmark does not use any special JavaScript features or syntax, such as `let`, `const` (with block scope), or arrow functions.

**Other alternatives**

For similar benchmarks, you can consider using:

* The `Array.prototype.length` property directly, like the "no var" option.
* Using a library like Lodash's `shuffle` function or a custom implementation to generate randomized arrays.
* Using alternative approaches, such as using `Math.random()` to generate random indices for array access.

Keep in mind that the choice of approach often depends on the specific requirements and constraints of the project.

Related benchmarks:

.length vs var randomized Arrays (version: 0)

Comparing performance of: no var vs var vs const vs accessing .length x 10 vs storing and accessing variable x 10

Created: 5 years ago by: Guest

Jump to the latest result

no var

var

const

accessing .length x 10

storing and accessing variable x 10

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):