Benchmark: forinfororfor*for

Script Preparation code:

var a = new Array(1000), random = Math.random, global, floor = Math.floor;
for(let i = 0; i < 1000; i++) a[i] = new Array(10).fill(random());

Tests:

forinfor
let length = a.length; for(let i = 0; i < length; i++) { let module = a[i]; for(let i2 = 0; i2 < module.length; i2++) global = module[i2]; }
for*for
let aLength = a[0].length; let length = a.length * aLength; for(let i = 0; i < length; i++) { let i2 = i % aLength, i3 = floor(i / aLength); global = a[i3][i2]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forinfor
for*for

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition**

The benchmark definition provides a script preparation code that creates an array `a` of 1000 elements, each containing another array of 10 elements filled with random values. It also defines some global variables: `random`, which is a reference to the built-in `Math.random()` function, and `floor`, which is a reference to the built-in `Math.floor()` function.

The script then uses two different approaches to iterate over the inner arrays:

1. **forin**: This approach uses the `for...in` loop to iterate over the outer array `a`, and for each element in `a`, it uses another `for...in` loop to iterate over the inner array.
2. **for*for**: This approach uses a simple loop with two variables, `i2` and `i3`, to index into the inner arrays.

**Test Cases**

The benchmark definition includes two individual test cases:

1. **forinfor**: This test case uses the `for...in` loop to iterate over the outer array `a`, and for each element in `a`, it uses another `for...in` loop to iterate over the inner array.
2. **for*for**: This test case uses a simple loop with two variables, `i2` and `i3`, to index into the inner arrays.

**Options Compared**

The benchmark is comparing two different approaches:

1. **forinfor**: Uses nested `for...in` loops
2. **for*for**: Uses a simple loop with two indexed variables

**Pros and Cons**

*   **forinfor**: Pros:
    *   Can be more intuitive for developers familiar with the `for...in` loop.
    *   May be faster due to the ability to use the loop's index directly.
    *   Cons:
    *   Can lead to slower performance due to the overhead of repeated property lookups.
*   **for*for**: Pros:
    *   Typically faster due to the reduced overhead of repeated property lookups.
    *   More cache-friendly, as it accesses elements in a more linear order.
    *   Cons:
    *   May be less intuitive for developers unfamiliar with indexed loops.

**Library and Special JS Features**

There are no libraries mentioned in the benchmark definition. However, `for...in` loop is a built-in JavaScript feature that allows iterating over an object's properties.

No special JavaScript features are used in this benchmark.

**Alternatives**

Other alternatives to compare could include:

*   Using `Array.prototype.forEach()` instead of `for...in`
*   Using a single loop with `i2` and `i3` variables for both inner arrays
*   Using an array of indices instead of two separate loops

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36

Browser/OS: Chrome 100 on Windows

View result in a separate tab

Test name	Executions per second
forinfor	929.6 Ops/sec
for*for	392.9 Ops/sec

Related benchmarks:

forinfororfor*for (version: 0)

fororfor

Comparing performance of: forinfor vs for*for

Created: 2 years ago by: Guest

Jump to the latest result

forinfor

for*for

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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