Toggle navigation
MeasureThat.net
Create a benchmark
Tools
Feedback
FAQ
Register
Log In
JS Loop Tests
(version: 4)
JS Memory Tests
Comparing performance of:
Map vs forLoop vs forEach vs forOf
Created:
2 years ago
by:
Registered User
Jump to the latest result
Script Preparation code:
var arr = new Array(1000000).fill(0)
Tests:
Map
arr.map(n => {});
forLoop
const length = arr.length; for (let i = 0; i < length; i++) {}
forEach
arr.forEach(n => {});
forOf
for (const num of arr) {}
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
Fork
Test case name
Result
Map
forLoop
forEach
forOf
Fastest:
N/A
Slowest:
N/A
Latest run results:
No previous run results
This benchmark does not have any results yet. Be the first one
to run it!
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark test cases. **What is being tested?** The benchmark tests various JavaScript loop constructs: `map`, `for` loops (with and without `const num of arr` syntax), and `forEach`. The goal is to compare the performance of these different loop approaches on a large array (`arr`) with 1 million elements, initialized with zeros. **Options being compared** The test cases compare: 1. **Map**: Uses the `map()` method to create a new array by applying a transformation function to each element. 2. **For Loop (Legacy)**: Uses a traditional `for` loop with an index variable (`i`) to iterate through the array. 3. **For Loop (New)**: Uses a `for...of` loop, which is a newer syntax that iterates over arrays without requiring an explicit index variable. 4. **ForEach**: Uses the `forEach()` method to execute a function on each element of the array. **Pros and Cons** Here's a brief summary of the pros and cons of each approach: 1. **Map**: * Pros: Efficient, concise, and easy to read. * Cons: Creates a new array, which can be memory-intensive for large datasets. 2. **For Loop (Legacy)**: * Pros: Classic, well-known syntax, and doesn't create a new array. * Cons: More verbose, requires manual index management, and can be slower due to the overhead of incrementing `i`. 3. **For Loop (New)**: * Pros: Improved readability, concise, and eliminates the need for an explicit index variable. * Cons: Requires modern JavaScript support, may have slower performance in older browsers. 4. **ForEach**: * Pros: Easy to read, concise, and doesn't require manual index management. * Cons: Creates a new proxy array, which can be memory-intensive for large datasets. **Library usage** None of the provided test cases explicitly use any external libraries, although `forEach()` method is an internal API in modern JavaScript. **Special JS features or syntax** The only special feature used in this benchmark is the **New For Loop Syntax (`for...of`)**, which was introduced in ECMAScript 2015 (ES6). This syntax allows iterating over arrays without requiring an explicit index variable. **Other alternatives** If you wanted to test alternative loop constructs, consider adding additional test cases for: * `reduce()` * `filter()` * `some()` and `every()` * Using native Web Workers or WebAssembly for parallelism Keep in mind that these alternatives would require significant changes to the benchmark script and might not provide meaningful comparisons with the original tests.
Related benchmarks:
fill vs map
fill vs for loop
TypedArray fill vs loop
For Loop Leng Inside and Outside
Comments
Confirm delete:
Do you really want to delete benchmark?