Benchmark: testtest - MeasureThat.net

Script Preparation code:

var x = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'g', 'a', 'c', 'l', 't', 'f', 'e', 'c', 'd', 't', 'h', 'a', 'y', 'l'];

Tests:

dedup1
var y = []; for (var i = x.length; i--;) { if (!y.includes(x[i])) y.unshift(x[i]); }
dedup2
var y = []; for (var i = 0, l = x.length; i < l; i++) { if (!y.includes(x[i])) y.push([i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
dedup1
dedup2

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the provided benchmark and its options.

**Benchmark Definition**

The benchmark definition represents a JavaScript microbenchmark that measures the performance of two different approaches for removing duplicates from an array while preserving the original order. The script preparation code is:

```javascript
var x = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'g', 'a', 'c', 'l', 't', 'f', 'e', 'c', 'd', 't', 'h', 'a', 'y', 'l'];
```

This array has duplicate values, which will be used to test the performance of different approaches for removing duplicates.

**Options Compared**

There are two options compared in this benchmark:

1. `dedup1`:
```javascript
var y = [];
for (var i = x.length; i--;) {
    if (!y.includes(x[i])) y.unshift(x[i]);
}
```

This approach uses the `includes()` method to check if an element is already present in the array, and then adds it to the beginning of the array using the `unshift()` method.

2. `dedup2`:
```javascript
var y = [];
for (var i = 0, l = x.length; i < l; i++) {
    if (!y.includes(x[i])) y.push([i]);
}
```

This approach also uses the `includes()` method to check if an element is already present in the array, but instead of adding it to the beginning of the array, it adds an index into an array (`[i]`) to represent the duplicate value.

**Pros and Cons**

Here are some pros and cons of each approach:

`dedup1`

Pros:

* Simple and easy to understand
* Does not require additional data structures (like arrays)

Cons:

* Has a time complexity of O(n^2) due to the use of `includes()`, which can be slow for large arrays.
* May cause performance issues if the array is very large.

`dedup2`

Pros:

* Can take advantage of optimized implementations of `includes()` under the hood
* Does not require additional data structures (like arrays)

Cons:

* Adds an index to a new array, which may incur overhead due to memory allocation.
* May have a higher constant factor than `dedup1` due to the use of `push()`.

**Library and Special JS Feature**

Neither approach uses any external libraries. However, it's worth noting that some browsers may optimize their own implementations of `includes()` or `unshift()`, which could affect the performance of these approaches.

If you're interested in exploring other alternatives, here are a few options:

* Using `Set` data structure to keep track of unique elements
```javascript
var y = new Set();
for (var i = 0; i < x.length; i++) {
    if (!y.has(x[i])) y.add(x[i]);
}
```
This approach has a time complexity of O(n) and is generally faster than the `includes()` method.
* Using a custom implementation of `unshift()` or `push()`
```javascript
function myPush(arr, element) {
    // optimized implementation of push()
}

var y = [];
for (var i = x.length; i--;) {
    if (!y.includes(x[i])) y.push([i]);
}
```
This approach would require a custom implementation of the `push()` method to avoid the overhead of memory allocation.

Keep in mind that these alternatives may be more complex and harder to understand, but can provide better performance for certain use cases.

Related benchmarks:

testtest (version: 0)

test

Comparing performance of: dedup1 vs dedup2

Created: 9 years ago by: Guest

Jump to the latest result

dedup1

dedup2

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):