Benchmark: Add value in the first position ofan array

Script Preparation code:

var aNumbers = [0,1,2,3];

Tests:

Unshift
aNumbers.unshift(4)
Concat
[4].concat(aNumbers)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Unshift
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 benchmark and its components.

**Benchmark Definition:**

The benchmark measures how fast two approaches are to add a value in the first position of an array. The arrays are defined as `aNumbers = [0,1,2,3];`.

**Options Compared:**

Two options are compared:

1. **Unshift**: This method adds a new element to the beginning of the array.
2. **Concat**: This method creates a new array by concatenating the original array with the value to be added.

**Pros and Cons of Each Approach:**

**Unshift:**

Pros:

* Efficient, as it only requires updating the internal array structure.
* Can be faster for small arrays or when adding many elements at once.

Cons:

* May cause unnecessary reallocations of memory if the original array is large.
* Can be slower than concat() for very large arrays due to overhead in handling boundary checks.

**Concat:**

Pros:

* Generally faster for large arrays, as it avoids reallocation and uses a more efficient allocation strategy.
* Easier to implement and understand for some developers.

Cons:

* Creates a new array object, which can be slower than updating the original array with unshift().
* More memory-intensive due to the creation of a new array.

**Library Usage:**

None of the test cases use any external libraries. Both options rely on built-in JavaScript methods (`unshift()` and `concat()`).

**Special JS Features/Syntax:**

None are explicitly mentioned or required for these two test cases. However, keep in mind that modern JavaScript versions (e.g., ECMAScript 2015+) introduced more efficient array methods like `set()`, which might be worth exploring in other benchmarks.

**Other Alternatives:**

For adding a value to the first position of an array, some developers may also consider using:

1. **Array.prototype.set(index, value)** (ECMAScript 2019+): This method can set the element at a specific index without shifting elements.
2. **Splice()**: While not directly applicable for the first position, splice() can be used to add a new element and shift existing ones.

However, in this specific benchmark, the focus is on comparing unshift() with concat(), which are the most common approaches.

Now that you've taken a deep breath, I hope this explanation helps!

Related benchmarks:

Add value in the first position ofan array (version: 0)

Two ways to add a value in the first position of an array.

Comparing performance of: Unshift vs Concat

Created: 9 years ago by: Registered User

Jump to the latest result

Unshift

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):