Benchmark: For with and without external variables

Script Preparation code:

var arr = [];
for (var i = 0; i < 10000; i++) {
  arr.push({
    Number: i
  });
};

var e = null;
var f = null;

function doWork(o, i) {
  e = o;
};

Tests:

1
for (var i = 0, len = arr.length; i <= len; i++) { e = arr[i]; };
2
var i = 0; var len = arr.length; for (; i <= len; i++) { f = arr[i]; };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
1
2

Fastest: N/A

Slowest: N/A

Latest 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 benchmark data.

**Benchmark Definition**

The provided benchmark definition is for measuring the performance of two different approaches to iterating over an array in JavaScript:

1. Using `for` loop with variable increment (`i <= len`)
2. Using `for` loop with variable assignment (`f = arr[i]`)

In both cases, a large array of 10,000 elements is created and then iterated over using the specified approach.

**Script Preparation Code**

The script preparation code creates an empty array `arr` and populates it with 10,000 objects, each containing a single property `Number` with a value ranging from 0 to 9,999.

Additionally, two variables `e` and `f` are declared and initialized to `null`, which will be used in the benchmark tests.

**Html Preparation Code**

There is no HTML preparation code provided for this benchmark, so we can assume that it's not necessary for this specific test case.

**Individual Test Cases**

We have two individual test cases:

1. "1" (Benchmark Definition: `for (var i = 0, len = arr.length; i <= len; i++) {\r\n  e = arr[i];\r\n};`)
2. "2" (Benchmark Definition: `var i = 0;\r\nvar len = arr.length;\r\n\r\nfor (; i <= len; i++) {\r\n  f = arr[i];\r\n};`)

Both test cases aim to measure the performance of iterating over the array using a `for` loop with different approaches.

**Library**

There is no explicit library mentioned in the benchmark definition. However, it's worth noting that the use of `var` and the syntax used for declaring variables (`e` and `f`) suggest that this benchmark might be compatible with older versions of JavaScript or environments where some features are not enabled by default (e.g., strict mode).

**Special JS Features/Syntax**

There doesn't appear to be any special JS features or syntax being tested in this benchmark. The test cases use standard `for` loops and variable declarations.

**Pros and Cons of Different Approaches**

Both approaches have their pros and cons:

1. Using `for` loop with variable increment (`i <= len`):
	* Pros: Can be more readable, especially for complex iterations.
	* Cons: May lead to off-by-one errors if not careful.
2. Using `for` loop with variable assignment (`f = arr[i]`):
	* Pros: Simplifies the iteration logic and reduces potential errors.
	* Cons: May require additional declarations for variables (like `len`) that need to be accessed.

**Other Alternatives**

There are other ways to iterate over an array in JavaScript, such as using:

1. Array.prototype.forEach(): This method is more modern and doesn't require explicit loop logic.
2. While loops: These can be used instead of traditional `for` loops for simple iterations.
3. For...of loops: Introduced in ECMAScript 2015, these loops provide a more concise way to iterate over arrays.

Keep in mind that the choice of iteration method often depends on personal preference, code readability, and performance considerations.

Related benchmarks:

For with and without external variables (version: 0)

Comparing performance of: 1 vs 2

Created: 8 years ago by: Guest

Jump to the latest result

1

2

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):