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for vs foreach vs some vs every vs for..of vs map with values
(version: 0)
Compare loop performance
Comparing performance of:
for vs foreach vs some vs every vs for..of vs map
Created:
5 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var array = new Array(100);
Tests:
for
for (var i = 0; i < array.length; i++) { array[i] = 1; }
foreach
array.forEach(function(i) { array[i] = 1; });
some
array.some(function(i) { array[i] = 1; });
every
array.every(function(i) { return array[i] === null; });
for..of
for (var i of array) { array[i] = 1; }
map
array.map(a => 1);
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (6)
Previous results
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Test case name
Result
for
foreach
some
every
for..of
map
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the benchmark and explain what's being tested, compared, and their pros and cons. **Benchmark Overview** The benchmark compares the performance of six different loop types in JavaScript: 1. `for` loops 2. `forEach` loops 3. `some` loops 4. `every` loops 5. `for...of` loops (introduced in ECMAScript 2015) 6. `map` functions with a callback **Loop Comparison** Each loop type has its own strengths and weaknesses: 1. **`for` loops**: Classic, straightforward loops that iterate over an array using the `length` property. Pros: easy to read, predictable performance. Cons: can be slow for large arrays due to repeated checks of the `length` property. 2. **`forEach` loops**: Introduced in ECMAScript 2009, these loops provide a concise way to iterate over an array without exposing the index. Pros: easy to read, good performance. Cons: can lead to errors if not used carefully. 3. **`some` loops**: Another introduced loop type (ECMAScript 2015), `some` loops short-circuit as soon as they find a true value. Pros: can be faster for arrays with false values. Cons: less intuitive than other loop types, potential performance issues if the callback is expensive. 4. **`every` loops**: Introduced in ECMAScript 2009, like `forEach`, these loops are designed to iterate over an array and return a boolean value. Pros: easy to read, good performance. Cons: less intuitive than other loop types. 5. **`for...of` loops** (ECMAScript 2015): These loops provide a concise way to iterate over arrays using the `values()` method. Pros: modern, easy to read, good performance. Cons: requires modern JavaScript engines and may not be supported in older browsers. 6. **`map` functions with a callback**: While not strictly a loop type, `map` functions can be used for iteration. They provide an efficient way to transform arrays without modifying the original data. Pros: concise, efficient. Cons: less intuitive than other loop types. **Library Usage** The benchmark uses the `Array.prototype.forEach`, `Array.prototype.some`, and `Array.prototype.every` methods, which are built-in JavaScript library functions. These methods provide a convenient way to iterate over arrays without exposing the index. **Special JS Features/Syntax** None of the tested loops or functions rely on special JavaScript features or syntax beyond what's covered in ECMAScript 2015 and earlier standards. **Alternatives** If you're interested in exploring alternative loop types or iteration methods, here are a few options: 1. **Closure-based iterations**: You can write custom loops using closures, which provide more control over the iteration process. 2. **Iterators**: Introduced in ECMAScript 2015, iterators allow for more flexible and efficient iteration over arrays and other data structures. 3. **Generators**: Similar to iterators, generators provide a way to iterate over data without exposing the index. Keep in mind that these alternatives may require more expertise and modern JavaScript engines to work effectively. In conclusion, this benchmark provides valuable insights into the performance characteristics of different loop types and iteration methods in JavaScript. By understanding the strengths and weaknesses of each approach, developers can choose the most suitable method for their specific use cases.
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