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js forEach vs for..of
(version: 0)
Comparing performance of:
forEach vs for..of
Created:
4 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var arr = []; for (var i = 0; i < 1000; i++) { arr[i] = i; } function someFn(i) { return i * 3 * 8; }
Tests:
forEach
arr.forEach(function (item){ someFn(item); })
for..of
for (const element of arr) { someFn(element); }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
forEach
for..of
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (iPhone; CPU iPhone OS 16_7_8 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Mobile/15E148 Safari/604.1
Browser/OS:
Mobile Safari 16 on iOS 16.7.8
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<iframe src="https://measurethat.net/Embed?id=539298" width="100%" height="500px"></iframe>
for..of
12K/s
forEach
11K/s
View exact numbers
Test name
Executions per second
✓
for..of
11,606 Ops/sec
forEach
11,355 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the JavaScript microbenchmark on MeasureThat.net. **Benchmark Definition** The benchmark measures the performance difference between two approaches: using `forEach` and using a traditional `for` loop with `of`. The script preparation code creates an array of 1000 elements, each initialized with its index. It also defines a function `someFn(i)` that takes an element as input and returns its result. **Options Compared** The benchmark compares two options: 1. **forEach**: Uses the `forEach` method to iterate over the array, calling `someFn(item)` for each element. 2. **for..of**: Uses a traditional `for` loop with the `of` clause to iterate over the array, calling `someFn(element)` for each element. **Pros and Cons of Each Approach** **ForEach:** Pros: * Concise and readable syntax * Easy to understand and maintain Cons: 1. Can be slower due to method call overhead 2. May have additional memory allocations or copies of the function argument **For..of:** Pros: 1. Often faster than `forEach` due to reduced method call overhead 2. Can be more efficient in terms of memory allocation and copying of arguments Cons: 1. Less readable and less intuitive syntax for some developers 2. May require additional setup or planning for complex iteration scenarios **Other Considerations** * The benchmark is run on a Mobile Safari 16 browser on an iPhone, which may have specific performance characteristics. * The execution frequency per second (ExecutionsPerSecond) is an important metric to consider when evaluating the performance of each approach. **Library Used** The `forEach` method and the `for...of` loop are built-in JavaScript features, so no libraries are used in this benchmark. **Special JS Features/Syntax** None mentioned explicitly, but it's worth noting that `for...of` is a relatively modern feature introduced in ECMAScript 2015 (ES6). If you're targeting older browsers or environments, you may need to use alternative approaches. **Alternative Approaches** Other alternatives for iterating over arrays include: * Using `Array.prototype.forEach.call()` or `Array.prototype.map()` * Implementing a custom iterator using `Array.prototype[Symbol.iterator]` * Using third-party libraries like Lodash or Ramda Keep in mind that the choice of iteration approach depends on your specific use case, performance requirements, and compatibility constraints.
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