Benchmark: push vs unshift - MeasureThat.net

Script Preparation code:

var arr = [];

Tests:

arrayPush-1
arr.push(1)
arrayUnshift-1
arr.unshift(1)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arrayPush-1
arrayUnshift-1

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark being tested on MeasureThat.net.

**What is being tested?**

The benchmark tests two different ways of adding an element to the end of an array in JavaScript: `push` and `unshift`. The test creates an empty array `arr` and then attempts to add the number 1 to it using both methods.

**Options compared**

There are only two options being compared:

*   `push`: This method adds a new element to the end of the array.
*   `unshift`: This method adds a new element to the beginning of the array.

**Pros and Cons of each approach:**

*   **`push`**: Pros:
    *   Faster, as it only needs to update the length of the array and then add the new element at the end.
    *   More memory-efficient, as it doesn't need to allocate extra space for the new element.
*   Cons:
    *   Can be slower if the array is very large and needs to be resized frequently.
    *   May not work correctly if the array is being used as a stack or queue.
*   **`unshift`**: Pros:
    *   Can be faster for certain use cases, such as when adding elements to the beginning of an array that will be processed in reverse order.
    *   Works correctly with arrays being used as stacks or queues.
*   Cons:
    *   Slower than `push`, especially for large arrays.
    *   Less memory-efficient, as it needs to allocate extra space for the new element.

**Other considerations:**

When choosing between `push` and `unshift`, consider the specific use case and requirements. If you need to add elements frequently to the end of an array, `push` is likely a better choice. However, if you're working with arrays that will be processed in reverse order or used as stacks/queues, `unshift` might be more suitable.

**Library usage:**

In this benchmark, none of the provided test cases use any external libraries.

**Special JS feature or syntax:**

This benchmark does not utilize any special JavaScript features or syntax beyond the standard `push` and `unshift` methods.

**Alternative approaches:**

There are other ways to add elements to an array in JavaScript, such as:

*   Using a loop to push elements onto the array.
*   Using a library like Lodash's `assignInPlace` method.
*   Creating a new array using the spread operator and then pushing elements onto it.

Here's an example of how you might use a loop with `push`:
```javascript
arr = [];
for (var i = 0; i < 10; i++) {
    arr.push(i);
}
```
And here's an example using the spread operator with `unshift`:
```javascript
const arr = [1, 2, 3];
const newArr = [...arr, 4, 5, 6];
newArr.unshift(0);
```

Related benchmarks:

push vs unshift (version: 0)

push vs unshift

Comparing performance of: arrayPush-1 vs arrayUnshift-1

Created: 8 years ago by: Guest

Jump to the latest result

arrayPush-1

arrayUnshift-1

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):