Benchmark: Javascript array deducplication 2.03

Script Preparation code:

var a = [1, 2, 3, 4, 5, 6, 5, 4];
var b = [6, 8, 2, 7, 6, 1, 4, 3];

function usingForEach(l1, l2) {
    let u = []

    l1.forEach(function(item) {
        if (u.indexOf(item) < 0)
            u.push(item);
    });

    l2.forEach(function(item) {
        if (u.indexOf(item) < 0)
            u.push(item);
    });

    return u;
};

function usingForEach2(l1, l2) {
    let u = []

    l1.forEach(function(item) {
        if (u.indexOf(item) == -1)
            u.push(item);
    });

    l2.forEach(function(item) {
        if (u.indexOf(item) == -1)
            u.push(item);
    });

    return u;
};

function usingSet(l1, l2) {
    let u = l1.concat(l2); // Joins the l1 and l2 arrays together using concatenation.
    return [...new Set(u)]; // Array is converted into a 'Set' in order to remove duplicates, then is converted back into an array using the spread operator.
};

Tests:

forEach Test
var test1 = usingForEach(a,b);
usingSet Test
var test2 = usingSet(a,b);
For each 2 test
var test1 = usingForEach2(a,b);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach Test
usingSet Test
For each 2 test

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 12; SM-G991B Build/SP1A.210812.016; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/105.0.5195.136 Mobile Safari/537.36 [FB_IAB/Orca-Android;FBAV/380.1.0.17.108;]

Browser/OS: Chrome Mobile 105 on Android

View result in a separate tab

Test name	Executions per second
forEach Test	2558798.2 Ops/sec
usingSet Test	909406.4 Ops/sec
For each 2 test	2476247.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested.

**Benchmark Definition:**

The benchmark is designed to test three different approaches for removing duplicates from two arrays using JavaScript:

1. `usingForEach`
2. `usingForEach2` (a variation of the first approach)
3. `usingSet`

The benchmark creates two sample arrays, `a` and `b`, and then defines three functions:

* `usingForEach`: uses the `forEach` method to iterate over both arrays and push unique elements into a new array.
* `usingForEach2`: uses the same approach as `usingForEach`, but with a subtle difference: it checks for equality using `== -1` instead of `< 0`.
* `usingSet`: joins the two arrays together using concatenation and then converts the resulting array to a Set (a data structure that automatically removes duplicates) before converting it back to an array.

**Options Compared:**

The benchmark is comparing three different approaches:

1. **Using `forEach`**: This approach uses the `forEach` method to iterate over both arrays and push unique elements into a new array.
2. **Using `forEach2`**: This approach is similar to `usingForEach`, but with a different equality check (`== -1` instead of `< 0`). This variation may have slightly better performance due to less overhead in the browser's internal `indexOf` method.
3. **Using Set**: This approach joins the two arrays together using concatenation and then converts the resulting array to a Set, which automatically removes duplicates.

**Pros and Cons:**

Here are some pros and cons of each approach:

* **Using `forEach`**:
	+ Pros: Simple and straightforward implementation.
	+ Cons: May have slower performance due to the browser's internal `indexOf` method being called on each iteration.
* **Using `forEach2`**:
	+ Pros: May have slightly better performance than `usingForEach` due to less overhead in the browser's internal `indexOf` method.
	+ Cons: Uses a different equality check, which may not be consistent with other browsers or platforms.
* **Using Set**:
	+ Pros: Fast and efficient, as Sets automatically remove duplicates.
	+ Cons: May require more memory to store the resulting Set.

**Other Considerations:**

* The benchmark does not consider issues like array indexing, out-of-bounds access, or potential null or undefined values in the input arrays.
* It also assumes that the input arrays are not extremely large (thousands of elements), as performance degradation may occur with very large inputs.

**Alternatives:**

If you're interested in exploring alternative approaches, here are a few:

1. **Using `Array.prototype.filter`**: Instead of using `forEach`, you can use the `filter` method to create a new array with only unique elements.
2. **Using `Array.prototype.reduce`**: You can use the `reduce` method to accumulate unique elements into an array.
3. **Using a library like Lodash's `uniqBy` function**: If you're working in a Node.js environment or need more advanced filtering capabilities, consider using a library like Lodash.

Keep in mind that these alternatives may have different performance characteristics and require additional setup or dependencies.

Related benchmarks:

Javascript array deducplication 2.03 (version: 0)

electric boogaloo

Comparing performance of: forEach Test vs usingSet Test vs For each 2 test

Created: 2 years ago by: Guest

Jump to the latest result

forEach Test

usingSet Test

For each 2 test

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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