Toggle navigation
MeasureThat.net
Create a benchmark
Tools
Feedback
FAQ
Register
Log In
Array initialization: preallocate vs push
(version: 0)
Comparing performance of:
Preallocate vs Push
Created:
7 years ago
by:
Guest
Jump to the latest result
Tests:
Preallocate
var N = 10000; var result = new Array(N); for (var i = 0; i < N; i++) { result[i] = N; }
Push
var N = 10000; var result = []; for (var i = 0; i < N; i++) { result.push(N); }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
Fork
Test case name
Result
Preallocate
Push
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
4 months ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:146.0) Gecko/20100101 Firefox/146.0
Browser/OS:
Firefox 146 on Windows
View result in a separate tab
Embed
Embed Benchmark Result
Test name
Executions per second
Preallocate
18513.1 Ops/sec
Push
17527.0 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the benchmark and its components. **Benchmark Definition** The provided JSON defines two benchmark cases: 1. **Preallocate**: This test case measures the performance of creating an array using the `new Array()` constructor and then populating it with 10,000 elements by assigning a value to each element. 2. **Push**: This test case measures the performance of creating an empty array and then populating it with 10,000 elements using the `push()` method. **Options Compared** The two benchmark cases compare the performance of two approaches: 1. **Preallocation**: Creating an array using the `new Array()` constructor and immediately populating it. 2. **Push**: Creating an empty array and then pushing elements onto it using the `push()` method. **Pros and Cons** **Preallocation (New Array())** Pros: * Can be faster because the array is created in a single step, reducing overhead. * Can lead to better memory locality, as all elements are initialized at once. Cons: * May require more memory upfront, depending on the size of the array. * Can be slower if the array is very large, due to the initial creation cost. **Push (Array.push())** Pros: * Requires less memory upfront, as only a single element needs to be allocated initially. * Can be faster for large arrays, since pushing elements one by one reduces overhead. Cons: * May lead to poorer memory locality, as each push operation creates a new allocation. * Can result in slower performance due to the repeated allocation and deallocation of memory. **Library** None of the benchmark cases use any libraries. The tests are self-contained JavaScript code that creates arrays and performs operations on them. **Special JS Feature/Syntax** There is no special JavaScript feature or syntax used in these benchmark cases. They use standard JavaScript syntax for creating arrays, loops, and push operations. **Other Alternatives** To measure the performance of array initialization, you could also consider other approaches, such as: * Using a library like `lodash` or `ramda`, which provide optimized array creation methods. * Implementing a custom array allocation function using native code (e.g., C++). * Measuring the performance of different data structures, such as arrays, linked lists, or vectors. In summary, this benchmark compares two common approaches to initializing and populating arrays in JavaScript: preallocation using `new Array()` and pushing elements onto an empty array using `push()`. The choice between these approaches depends on the specific use case and performance requirements.
Related benchmarks:
Array spread vs. push performance
Array construct vs array push
Javascript Array Spread vs Push
Array Push vs. Index Access
Spread vs Push when adding into array
Comments
Confirm delete:
Do you really want to delete benchmark?