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arr unshift vs push + reverse (size 50 array)
(version: 0)
Comparing performance of:
unshift vs push + reverse
Created:
2 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var arr = [];
Tests:
unshift
for (let i = 0; i < 50; i++){ arr.unshift(i); }
push + reverse
for (let i = 0; i < 50; i++){ arr.push(i); } arr.reverse();
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
unshift
push + reverse
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0
Browser/OS:
Firefox 140 on Linux
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=613935" width="100%" height="500px"></iframe>
unshift
11K/s
push + reverse
102/s
View exact numbers
Test name
Executions per second
✓
unshift
10,909 Ops/sec
push + reverse
102 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested. **Benchmark Overview** The benchmark compares two approaches to add elements to an array: `arr.unshift(i)` and `arr.push(i) + arr.reverse()`. The test case creates an empty array, fills it with 50 elements using one of these methods, and then measures the execution time. **Options Compared** There are two options being compared: 1. **unshift**: This method adds a new element to the beginning of the array. 2. **push + reverse**: This approach first adds a new element to the end of the array using `arr.push(i)`, and then reverses the entire array using `arr.reverse()`. **Pros and Cons** * **Unshift**: + Pros: Efficient for adding elements to the beginning of the array, as it only requires updating the index of each element. + Cons: Can be slower than `push` because it involves updating an internal array structure, which can lead to cache misses. * **Push + reverse**: + Pros: Can be faster than `unshift` because reversing the entire array at once can reduce cache locality issues. However, this approach is less efficient for small arrays or frequent insertions. + Cons: Requires two operations (push and reverse), which can increase overall execution time. **Library** The benchmark does not use any external libraries beyond what's built into JavaScript (e.g., `Array.prototype.unshift`, `Array.prototype.push`, `Array.prototype.reverse`). **Special JS Feature or Syntax** There is no special JS feature or syntax being tested in this benchmark. The focus is on the performance comparison between two common array manipulation methods. **Other Considerations** * The benchmark creates a new array of size 50 for each test case, which can impact execution time. * The `unshift` method may perform better if the array grows quickly because it only requires updating indices, while `push + reverse` involves reversing the entire array. * In real-world scenarios, you might not create an empty array and fill it with elements in a single loop. This benchmark simplifies the test case to focus solely on the performance comparison. **Other Alternatives** If you're interested in exploring other approaches or variations, consider these alternatives: 1. **Array.prototype.splice**: Instead of `unshift` and `push`, use `splice` to remove and add elements from the array. 2. **Array.prototype.concat**: Compare the performance of concatenating multiple arrays using `concat` versus creating a new array with `push`. 3. **For-loops vs Array methods**: Compare the performance of using traditional for-loops (e.g., `for (var i = 0; i < 50; ++i) { arr[i] = i; }`) versus using built-in array methods like `forEach`, `map`, or `reduce`. 4. **Array initialization vs allocation**: Investigate how the performance of initializing an array with a fixed size (`arr = new Array(50);`) compares to dynamically allocating memory using `new Int32Array()` or other native array types. Keep in mind that these alternative benchmarks will likely have different test cases and focus on specific aspects of JavaScript performance.
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