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Object.keys vs for in vs Object.getOwnPropertyNames
(version: 0)
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Comparing performance of:
asta castiga btw vs meh vs meh 2
Created:
6 years ago
by:
Guest
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Script Preparation code:
var obj = { $props : ['a','b','c'], a:1, b:2, c:3 }
Tests:
asta castiga btw
let n = 0; for (let k in obj) { n++; }
meh
const arr = Object.keys(obj); let n = 0; for (let i = 0; i < arr.length; i++) { n++; }
meh 2
const arr = Object.getOwnPropertyNames(obj); let n = 0; for (let i = 0; i < arr.length; i++) { n++; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
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Test case name
Result
asta castiga btw
meh
meh 2
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net. **Benchmark Overview** The provided benchmark compares three ways to iterate over an object in JavaScript: `for...in`, `Object.keys()`, and `Object.getOwnPropertyNames()`. The goal is to measure which approach is fastest, most efficient, or perhaps has some other advantage. **Options Compared** We have two options compared: 1. **`for...in`**: This traditional way of iterating over an object's properties uses the `for...in` loop syntax and returns both enumerable and non-enumerable properties. 2. **`Object.keys()`**: This method returns only the enumerable properties of an object as an array, allowing for more fine-grained control over iteration. 3. **`Object.getOwnPropertyNames()`**: Similar to `Object.keys()`, but also includes non-enumerable properties in the result. **Pros and Cons** Here's a brief rundown of each approach: * **`for...in`**: * Pros: Simple, easy to read, works with all objects (including non-enumerable properties). * Cons: Returns both enumerable and non-enumerable properties, can lead to unexpected behavior if not used carefully. * **`Object.keys()`**: * Pros: Fast, efficient, and safe, as it only returns enumerable properties. Also, more readable than `for...in`. * Cons: Does not include non-enumerable properties, might be less intuitive for some developers. * **`Object.getOwnPropertyNames()`**: * Pros: Returns all properties (enumerable and non-enumerable), which can be useful in certain scenarios. It also is more accurate than `Object.keys()` when iterating over a large object with many non-enumerable properties. When deciding between these options, consider the specific requirements of your project: * **Performance**: If speed is crucial, use `Object.keys()`. * **Readability**: Choose `for...in` for its simplicity and familiarity. * **Accuracy**: Opt for `Object.getOwnPropertyNames()` when you need to ensure all properties are processed. **Library Usage** None of the provided benchmark definitions rely on any external libraries. The only library-like functionality is inherent to the JavaScript language itself, such as `Object.keys()`, `Object.getOwnPropertyNames()`, and the `for...in` loop. **Special JS Features or Syntax** The provided benchmark examples are straightforward and do not use any advanced JavaScript features like async/await, arrow functions, or classes. The focus is on understanding how to iterate over objects using different approaches. By understanding these three options for iterating over objects, developers can choose the best approach for their specific needs, considering factors such as performance, readability, and accuracy. **Other Alternatives** Some other alternatives for iterating over objects include: * **Using `Array.prototype.forEach()`**: This method is similar to `Object.keys()`, but uses an array of properties instead. It's a good alternative when you need to process all enumerable properties. * **Using `for...of` loops**: Introduced in ECMAScript 2015, these loops provide an even more concise and readable way to iterate over objects with specific iterables. Keep in mind that these alternatives might not be directly comparable to the provided options, but they can offer different advantages depending on your use case.
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