Benchmark: Array.prototype.concat vs splice for joining two arrays2

Tests:

immutable with concat
var a = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" , "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello"] var b = [ "hello", "hello", "hello"] var other = b.concat(a)
direct mutation with splice + spread
var a = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" , "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello"] var b = [ "hello", "hello", "hello"] a.splice(0, 0, ...b);

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Suite status: <idle, ready to run>

Previous results

Test case name	Result
immutable with concat
direct mutation with splice + spread

Fastest: N/A

Slowest: N/A

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

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The provided benchmark definition json represents two test cases for joining two arrays using different approaches:

1. `Array.prototype.concat` (Test Case 1: "immutable with concat")
2. `splice` with spread operator (`...`) (Test Case 2: "direct mutation with splice + spread")

**Array.prototype.concat**

In this approach, the `concat` method is used to join two arrays. The first array (`a`) is created with a large number of elements, while the second array (`b`) has only a few elements. The `concat` method returns a new array that contains all elements from both arrays.

```javascript
var a = [ ... ]; // long array
var b = [ ... ]; // short array
var result = a.concat(b);
```

**Pros:**

* Simple and straightforward approach.
* No mutation of the original arrays.

**Cons:**

* Creates a new array, which can lead to increased memory usage and garbage collection.
* Not suitable for large datasets or performance-critical applications.

**splice with spread operator**

In this approach, the `splice` method is used to insert elements from the second array (`b`) into the first array (`a`). The `...` operator is used to spread the elements of `b` into the `splice` call.

```javascript
var a = [ ... ]; // long array
a.splice(0, 0, ...b); // insert elements of b into a
```

**Pros:**

* No creation of a new array.
* Suitable for large datasets and performance-critical applications.

**Cons:**

* Mutates the original arrays (`a`).
* Can lead to unexpected behavior if not used carefully (e.g., if `b` is larger than `a`, it will truncate `a`).

**Other alternatives**

1. **Array.prototype.reduce**: You can use the `reduce` method to join two arrays by iterating over each element of one array and concatenating it with the accumulator of the other array.

```javascript
var a = [ ... ];
var b = [ ... ];
var result = a.reduce((acc, curr) => acc.concat(b), []);
```

2. **Array.prototype.forEach**: You can use the `forEach` method to iterate over each element of one array and push it into another array.

```javascript
var a = [ ... ];
var b = [ ... ];
a.forEach(curr => b.push(curr));
```

However, these alternatives may not be as efficient or scalable as using `concat` or `splice` with spread operator for large datasets.

**Library usage**

There is no explicit library usage mentioned in the benchmark definition json. However, if you were to write a custom implementation that uses a third-party library, you might consider using libraries like Lodash or Underscore.js, which provide utility functions for working with arrays and objects.

**Special JS features or syntax**

The benchmark definition does not use any special JavaScript features or syntax (e.g., async/await, Promises, Arrow functions).

Related benchmarks:

Array.prototype.concat vs splice for joining two arrays2 (version: 0)

Comparing performance of: immutable with concat vs direct mutation with splice + spread

Created: 6 years ago by: Guest

Jump to the latest result

immutable with concat

direct mutation with splice + spread

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):