Benchmark: Wtf why is the last one fastest?!

Script Preparation code:

var a = [ "a", "b" ];
var b = { a: "a", b: "b" };

Tests:

Array get
let c = a[ 0 ] + a[ 1 ];
Object get
let c = b.a + b.b;
Array new and get
let z = [ "a", "b" ] let c = a[ 0 ] + a[ 1 ];
Object set and get
let z = { a: "a", b: "b" }; let c = z.a + z.b;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array get
Object get
Array new and get
Object set and get

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36

Browser/OS: Chrome 116 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array get	14353846.0 Ops/sec
Object get	14854926.0 Ops/sec
Array new and get	14315615.0 Ops/sec
Object set and get	1007339072.0 Ops/sec

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 data and explain what is being tested, compared, and their pros and cons.

**Benchmark Definition JSON**

The provided JSON represents a JavaScript microbenchmark with two scripts: `a` and `b`. Script `a` contains an array with two elements, while script `b` defines an object with two properties (`a` and `b`). The benchmark compares different approaches to access the first element of each array/object.

**Script Preparation Code**

The preparation code for each script is:

- For `a`: `var a = [ "a", "b" ];`
- For `b`: `var b = { a: "a", b: "b" };`

These scripts create an array with two elements and an object with two properties, respectively.

**Html Preparation Code**

The html preparation code is empty (`null`), indicating that the benchmark does not require any HTML setup or execution environment changes.

**Test Cases**

There are four test cases:

1. `Array get`: Accessing the first element of array `a`.
2. `Object get`: Accessing the property `a` of object `b`.
3. `Array new and get`: Creating a new array with two elements and then accessing its first element.
4. `Object set and get`: Creating an object with properties `a` and `b`, setting their values, and then accessing them.

**Benchmark Comparison**

The benchmark compares the execution time of different approaches to access the first element of each array/object:

- `Array get`: Accessing `a[0]`.
- `Object get`: Accessing `b.a`.
- `Array new and get`: Creating a new array `[ "a", "b" ]` and then accessing its first element (`a[0]`).
- `Object set and get`: Setting the values of object properties `z.a = "a"` and `z.b = "b"`, and then accessing them (`z.a + z.b`).

**Pros and Cons**

Here are some pros and cons for each approach:

1. **Array Get**: Simple and direct access to an array element. Pros: Fast, simple. Cons: Does not create a new object or array.
2. **Object Get**: Accessing an object property by name. Pros: Often more readable and easier to understand than array indexing. Cons: May be slower due to the extra step of accessing the property.
3. **Array New and Get**: Creating a new array and then accessing its first element. Pros: Allows for creating multiple arrays without reusing the same one. Cons: More complex, may incur additional overhead.
4. **Object Set and Get**: Setting values in an object and then accessing them. Pros: Can be useful for more complex operations or when working with objects that need to be updated. Cons: May slow down due to the extra step of setting the value.

**Library and Special JS Features**

- The `var` keyword is used, which was the standard way to declare variables in older versions of JavaScript.
- No special JavaScript features are mentioned, but note that some newer JavaScript engines might support newer features like arrow functions or async/await.

**Other Alternatives**

Other alternatives for accessing array elements and object properties could be:

* `Array.prototype[0]` instead of `a[0]`
* `Object.values()` or `Object.keys()` to access all values or keys of an object
* Creating a new array with the desired size using `new Array(size)` instead of creating it dynamically

Keep in mind that these alternatives might not be directly comparable to the original benchmark, as they may introduce additional overhead or have different performance characteristics.

Related benchmarks:

Wtf why is the last one fastest?! (version: 0)

What is going on?!

Comparing performance of: Array get vs Object get vs Array new and get vs Object set and get

Created: one year ago by: Guest

Jump to the latest result

Array get

Object get

Array new and get

Object set and get

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):