Toggle navigation
MeasureThat
.net
Create a benchmark
Tools
Feedback
Feature Requests
FAQ
Register
Log In
for vs foreach vs some vs for..of and reduce
(version: 0)
Benchmark.js
Compare loop performance
Comparing performance of:
for vs foreach vs some vs for..of vs reduce
Created:
4 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var array = new Array(1000).map( () => 1);
Tests:
for
for (var i = 0; i < array.length; i++) { array[i]; }
foreach
array.forEach(function(i) { array[i]; });
some
array.some(function(i) { array[i]; });
for..of
for (var i of array) { array[i]; }
reduce
array.reduce( function(a, b ) { a+b; }, 1 )
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
Previous results
Fork
Test case name
Result
for
foreach
some
for..of
reduce
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36
Browser/OS:
Chrome 126 on Mac OS X 10.15.7
View result in a separate tab
Embed
Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=538518" width="100%" height="500px"></iframe>
foreach
479K/s
reduce
469K/s
some
468K/s
for..of
26K/s
for
15K/s
View exact numbers
Test name
Executions per second
✓
foreach
479,112 Ops/sec
reduce
469,357 Ops/sec
some
467,732 Ops/sec
for..of
25,947 Ops/sec
for
15,346 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks. The provided JSON represents a benchmark test that compares the performance of different loop constructs: `for`, `foreach`, `some`, and `for..of` with the additional `reduce` method. We'll break down each option, their pros and cons, and other considerations. **Loop Constructs** 1. **For Loop (`for (var i = 0; i < array.length; i++) { ... }`)**: * Pros: Simple, efficient, and widely supported. * Cons: Can lead to off-by-one errors if not used carefully. It's a more manual approach, requiring the programmer to manage the loop variable. 2. **Foreach Loop (`array.forEach(function(i) { array[i]; });`)**: * Pros: Easy to read and write, as it doesn't require explicit indexing. The callback function is executed for each element in the array. * Cons: Can be slower than a `for` loop due to the overhead of the callback function invocation. 3. **Some Loop (`array.some(function(i) { array[i]; });`)**: * Pros: Similar to `foreach`, but returns a boolean indicating whether at least one element matches the condition. * Cons: Not as intuitive as `foreach` or `for`, as it implies a "some" success criterion. It can also lead to slower performance due to the callback function invocation. 4. **For..of Loop (`for (var i of array) { array[i]; }`)**: * Pros: Introduced in ECMAScript 2015, this loop is designed for iterating over arrays and other iterable objects. It's concise and easy to read. * Cons: Not as widely supported as older loop constructs. The `i` variable is also immutable, which might be surprising for some developers. **Reduce Method** 1. **Reduce Method (`array.reduce(function(a, b) { a+b; }, 1)`)**: * Pros: Efficiently reduces an array to a single value (e.g., sum or product). It's often used in conjunction with other loop constructs. * Cons: May not be as intuitive for simple iteration tasks. The callback function expects the accumulator (`a`) and current element (`b`). Now, let's consider special JavaScript features: * **Arrow functions**: Used in `foreach`, `some`, and `reduce` to define small, anonymous functions. They're concise but can lead to issues if not used carefully (e.g., capturing outer scope variables). * **Immutable variable declarations**: Used in the `for..of` loop to declare a new variable (`i`) that's reassigned on each iteration. This is a deliberate design choice to avoid mutable state. Other alternatives for loop constructs: * **Array.prototype.map()`: Not tested here, but it can be used to create a new array with transformed elements. * **Array.prototype.filter()**: Also not tested here, as its primary purpose is data filtering rather than iteration. * **Set or Map data structures**: Could potentially replace arrays in certain scenarios, especially for fast membership testing or key-value pairs. However, they're more complex and less intuitive for simple iteration tasks. In summary, the benchmark test provides a fair comparison of different loop constructs and the `reduce` method, highlighting their strengths and weaknesses.
Related benchmarks
map vs forEach Chris v2b
Array fill map, vs for i loop
Comments
Confirm delete:
Do you really want to delete benchmark?