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Get index with forEach vs for...of over entries
(version: 0)
Comparing performance of:
forEach vs for...of over entries
Created:
4 years ago
by:
Guest
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Script Preparation code:
var array = Array.from({ length: 100 });
Tests:
forEach
array.forEach((el, i) => { console.log(i); })
for...of over entries
for (const [i, el] of array.entries()) { console.log(i); }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
forEach
for...of over entries
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to explain the benchmark and its results. **What is tested?** The benchmark tests two approaches to iterate over an array: `forEach` and `for...of` with `entries`. The test case uses JavaScript, which is a high-level, dynamic language that allows for extensive manipulation of data structures. The specific task being measured is the execution time and performance of these two approaches. **Options compared** There are only two options being compared: 1. **`forEach"`**: This method iterates over an array using a callback function. In this case, each element in the array is passed to the callback function as an argument `el`, along with its index `i`. 2. **`for...of` with `entries`** : This method uses a loop syntax to iterate over an iterable (in this case, an array). The `entries` property returns an iterator that yields each key-value pair in the array. **Pros and Cons of each approach** 1. **`forEach"`**: * Pros: Simple, straightforward, easy to read and write. * Cons: Can be less efficient than other methods, especially for large arrays, as it creates a new scope for the callback function on each iteration. 2. **`for...of` with `entries`**: * Pros: More efficient than `forEach`, especially for large arrays, as it avoids creating a new scope and uses the iterator's optimized internal workings. * Cons: May require more setup and boilerplate code (e.g., declaring an iterator variable), which can make it less readable. **Library usage** There is no library explicitly used in this benchmark. The `Array.from()` method is a built-in JavaScript function, but the `entries` property on arrays is also a native feature of JavaScript, not a library. **Special JS features or syntax** The benchmark uses the following special JavaScript feature: * **Template literals**: Used in the script preparation code to define an array using `Array.from({ length: 100 })`. * **Arrow functions**: Used in the callback function of the `forEach` method. * **For-of loop with entries**: A new syntax introduced in ECMAScript 2015 (ES6) that allows iterating over arrays and other iterables. **Other alternatives** If you're interested in exploring alternative approaches to iteration, here are a few examples: 1. **`map()` and `reduce()`**: These methods can be used for more complex operations on arrays, such as transforming data or accumulating results. 2. **`filter()`**: Similar to `forEach`, but returns a new array with only the elements that pass the test. 3. **`set()`**: A newer data structure introduced in ECMAScript 2015 (ES6) that allows for efficient iteration and membership testing. Keep in mind that each approach has its own strengths and weaknesses, and the best choice depends on the specific use case and requirements.
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