Benchmark: Get last array element

Script Preparation code:

var array = [];

for(var i = 0; i < 100000; i++){array.push(Math.random());}

Tests:

pop
array.pop();
length
array[array.length - 1]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
pop
length

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's dive into explaining the benchmark.

**What is tested?**

The provided JSON represents two individual test cases that measure the performance of JavaScript operations on an array.

1. The first test case measures the execution time of the `array.pop()` operation, which removes and returns the last element of the array.
2. The second test case measures the execution time of accessing the last element of the array using the index `[array.length - 1]`.

**Options compared**

In this benchmark, only two options are being compared:

* `array.pop()`: This method modifies the original array by removing and returning the last element.
* `[array.length - 1]`: This approach accesses the last element directly using its index.

**Pros and Cons of each approach:**

1. **`array.pop()`**
	* Pros:
		+ Eliminates the need to specify the index, making it more concise.
		+ May be faster since it avoids the overhead of accessing an array element by index (although this is often negligible).
	* Cons:
		+ Modifies the original array, which can lead to unexpected behavior in some contexts.
		+ Creates a new object if the array is not modified, leading to unnecessary memory allocation.
2. **[array.length - 1]**
	* Pros:
		+ Does not modify the original array.
		+ Avoids potential issues with `pop()` modifying the array.
	* Cons:
		+ Requires specifying the index, which can make the code more verbose.

**Library usage**

There is no explicit library mentioned in the provided JSON. However, it's worth noting that `array.pop()` and `[array.length - 1]` are built-in JavaScript operators.

**Special JS feature or syntax**

None of the benchmarked operations use any special JavaScript features or syntax beyond what's commonly used.

**Other alternatives**

If you're looking for alternative ways to access the last element of an array, you could consider using `Array.prototype.at()` (introduced in ECMAScript 2019), which returns a reference to the element at the specified index:
```javascript
array.at(-1);
```
Keep in mind that this method is not yet widely supported in older browsers.

In summary, the benchmark compares two common approaches for accessing the last element of an array: `array.pop()` and `[array.length - 1]`. While both have their pros and cons, `array.pop()` can be a more concise option, but it modifies the original array. The `[array.length - 1]` approach is safer and avoids modifying the array, but requires specifying the index.

Related benchmarks:

Get last array element (version: 0)

Comparing performance of: pop vs length

Created: 9 years ago by: Guest

Jump to the latest result

pop

length

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):