Benchmark: arrayloops - MeasureThat.net

HTML Preparation code:

<script>
var arr1 = [];
var arr2 = [];
var arr3 = [];
</script>

Tests:

shift
arr1.push(Date.now()); if (arr1.length > 5) arr1.shift();
manual
const newEntry = Date.now(); if (arr2.length < 5) { arr2.push(newEntry); } else { for (let i = 1; i < 5; i++) { arr2[i - 1] = arr2[i]; } arr2[4] = newEntry; }
splice
const newEntry = Date.now(); if (arr3.length >= 5) arr3.splice(0, 1); arr3 = [...arr3, newEntry];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
shift
manual
splice

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):

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I'd be happy to help you understand the JavaScript microbenchmark, MeasureThat.net.

**What is being tested?**

MeasureThat.net tests three different approaches for removing elements from an array: `shift`, `splice`, and manual implementation (which we'll discuss in more detail later). The benchmark measures the execution time of each approach on a 5-element array filled with Date.now() values.

**Options compared**

The three options being compared are:

1. **`shift`**: This method removes the first element from the end of the array and returns it. It's implemented as `arr1.push(Date.now()); if (arr1.length > 5) arr1.shift();`.
2. **Manual implementation**: This approach uses a loop to remove elements from the start of the array until there are less than 5 elements. It's implemented as `const newEntry = Date.now(); if (arr2.length < 5) { arr2.push(newEntry); } else { for (let i = 1; i < 5; i++) { arr2[i - 1] = arr2[i]; } arr2[4] = newEntry; }`.
3. **`splice`**: This method removes a specified number of elements from the array and returns them as an array. It's implemented as `const newEntry = Date.now(); if (arr3.length >= 5) arr3.splice(0, 1); arr3 = [...arr3, newEntry];`.

**Pros and Cons**

Here are some pros and cons for each approach:

* **`shift`**: Pros: Simple to implement, likely to be fast since it only involves a single operation. Cons: May not be the most efficient way to remove elements from an array, as it requires shifting all remaining elements down.
* **Manual implementation**: Pros: Can be optimized for specific use cases (e.g., removing a fixed number of elements). Cons: More complex and slower than `shift` due to the loop overhead.
* **`splice`**: Pros: Fast and efficient since it uses a native method that's implemented in C++. Cons: May incur additional overhead if not used carefully, as it requires creating an array copy.

**Library and special JS features**

In this benchmark, no libraries or special JavaScript features are explicitly mentioned. However, `Date.now()` is used to populate the arrays with values, which is a common pattern in JavaScript benchmarks.

**Considerations**

When choosing between these approaches, consider the specific use case and performance requirements of your application. If you need to remove elements from an array frequently, `shift` or manual implementation might be suitable. However, if you need to remove a large number of elements or require high performance, `splice` is likely the best choice.

**Other alternatives**

If you're looking for alternative approaches to removing elements from an array in JavaScript, consider:

1. **`array.prototype.slice()`**: A more modern alternative to `shift`, which creates a new array with the desired elements.
2. **`filter()`**: A method that creates a new array with elements that pass a test (in this case, no elements).
3. **`map()` and `reduce()`**: Methods that can be used in combination to create a new array with the desired elements.

Keep in mind that these alternatives may have different performance characteristics compared to `shift`, `splice`, or manual implementation, so consider your specific use case when choosing an approach.

Related benchmarks:

arrayloops (version: 0)

Comparing performance of: shift vs manual vs splice

Created: 5 years ago by: Guest

Jump to the latest result

shift

manual

splice

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):