Benchmark: spread vs concat vs unshift

Script Preparation code:

var array = [1,2,3];

Tests:

arrayUnshift
array.unshift(0);
arrayConcat
array = [0].concat(array)
arraySpread
array = [0, ...array]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arrayUnshift
arrayConcat
arraySpread

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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I'd be happy to explain the JavaScript microbenchmark provided by MeasureThat.net.

**Overview of the Benchmark**

The benchmark measures the performance difference between three different ways to add an element to the end of an array in JavaScript:

1. `unshift()`
2. `concat()`
3. `spread` (using the syntax `[...array]`)

These operations are commonly used in various scenarios, such as adding a new element to the beginning of an array or merging two arrays.

**Options Compared**

The benchmark compares the performance of these three approaches:

* `unshift()`: This method adds one or more elements to the beginning of an array.
* `concat()`: This method returns a new array containing all elements from the original array, followed by any additional elements.
* `spread` (using `[...array]`): This is a syntax feature introduced in ECMAScript 2015 that allows spreading an array into another array.

**Pros and Cons of Each Approach**

Here's a brief summary of each approach:

* `unshift()`:
	+ Pros: Efficient for small arrays, as it only needs to update the internal pointers.
	+ Cons: Can lead to slower performance for large arrays due to the overhead of updating multiple elements.
* `concat()`:
	+ Pros: More efficient than `unshift()` for large arrays, but creates a new array object, which can be expensive in terms of memory allocation and garbage collection.
	+ Cons: Less efficient than `unshift()` for small arrays.
* `spread` (using `[...array]`):
	+ Pros: Fast and efficient, as it only needs to create a new array with the spread elements.
	+ Cons: Requires support for ECMAScript 2015 syntax, which may not be supported by older browsers or environments.

**Library and Syntax Used**

The benchmark uses the following libraries and syntax:

* No external libraries are used in this benchmark.
* The `spread` syntax is a built-in feature of JavaScript introduced in ECMAScript 2015.

**Other Considerations**

When choosing an approach, consider the size of the array, as well as any specific requirements or constraints for your use case. For small arrays, `unshift()` may be sufficient, while larger arrays may benefit from `concat()` or `spread`.

Additionally, if you need to perform multiple operations on the same array, it's essential to consider the overhead of creating temporary objects and garbage collection.

**Alternatives**

If you're looking for alternative approaches, you can also consider:

* Using `Array.prototype.slice()` with the spread syntax: `[...array.slice()]`
* Using a library like Lodash or Ramda, which provide optimized implementations of array operations.
* Using a different data structure, such as an array-like object or a linked list.

Keep in mind that these alternatives may have their own trade-offs and performance characteristics, so it's essential to test and evaluate them based on your specific use case.

Related benchmarks:

spread vs concat vs unshift (version: 0)

spread vs concat vs unshift

Comparing performance of: arrayUnshift vs arrayConcat vs arraySpread

Created: 8 years ago by: Guest

Jump to the latest result

arrayUnshift

arrayConcat

arraySpread

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):