Benchmark: Array.concat and Babel ES5

Script Preparation code:

var previousContexts = [123, 456, 678, 123, 456, 678, 123, 456, 678, 123, 456, 678, 123, 456, 678, 123, 456, 678];
var newCallContexts = [123, 456, 678, 123, 456, 678, 123, 456, 678, 123, 456, 678, 123, 456, 678, 123, 456, 678];

Tests:

Babel
function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } } var joined = [].concat( _toConsumableArray(previousContexts), _toConsumableArray(newCallContexts) );
New array concat
var joined = [].concat(previousContexts, newCallContexts);
Exist array concat
var joined = previousContexts.concat(newCallContexts);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Babel
New array concat
Exist array concat

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares three different approaches to concatenate arrays: `Array.concat()`, `[].concat()`, and a custom implementation using `_toConsumableArray()` (only used in the Babel test case).

**What is being tested?**

1. **`Array.concat()`**: This method creates a new array by concatenating two or more arrays. The benchmark tests how fast this method is compared to other approaches.
2. **`[].concat()`**: In JavaScript, when you use `[]` as an array literal, it's not actually an array at first glance. To make it behave like an array, you need to use the bracket notation (`[]`). This approach creates a new array by concatenating two or more arrays using the dot notation.
3. **Custom implementation (`_toConsumableArray()`)**: This custom function takes an array as input and returns a new array with the same elements. It's used in the Babel test case to compare the performance of this custom approach.

**Options compared**

The benchmark compares three options:

1. `Array.concat()`
2. `[].concat()` (dot notation)
3. Custom implementation (`_toConsumableArray()`) (only in the Babel test case)

**Pros and Cons**

Here are some pros and cons for each option:

1. **`Array.concat()`**:
	* Pros: Simple, widely supported, and well-documented.
	* Cons: Creates a new array object on the heap, which can lead to performance issues when dealing with large arrays.
2. **`[].concat()` (dot notation)**:
	* Pros: Can be faster than `Array.concat()`, as it doesn't create a new array object on the heap.
	* Cons: Less widely supported and less well-documented compared to `Array.concat()`.
3. **Custom implementation (`_toConsumableArray()`)**:
	* Pros: May offer better performance, especially when dealing with large arrays.
	* Cons: Not as widely supported or well-documented as the other two options.

**Library usage**

In the benchmark, the `_toConsumableArray()` function is used in the Babel test case. This function is not a built-in JavaScript function but rather a custom implementation designed to optimize array concatenation. Its purpose is to create a new array with the same elements as the input array, without creating intermediate objects or arrays.

**Special JS feature/syntax**

The benchmark uses a modern JavaScript feature called "arrow functions" (`=>`) in some test cases. Arrow functions are a shorthand way of defining small functions and are widely supported in modern browsers.

**Other alternatives**

If you're interested in exploring alternative approaches to array concatenation, here are a few options:

1. **`Array.prototype.push()`**: Instead of concatenating arrays, you can use `push()` to add elements to an existing array.
2. **`Array.prototype.splice()`**: You can use `splice()` to remove and replace elements in an array, which can be more efficient than concatenation for large arrays.
3. **Using a library like Lodash**: Lodash provides various utility functions, including ones for array manipulation and concatenation.

Keep in mind that the choice of approach depends on your specific use case and performance requirements.

Related benchmarks:

Array.concat and Babel ES5 (version: 1)

Comparing performance of: Babel vs New array concat vs Exist array concat

Created: 8 years ago by: Registered User

Jump to the latest result

Babel

New array concat

Exist array concat

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):