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for-in vs object.entries
(version: 0)
Comparing performance of:
for-in vs Object.keys vs Object.entries
Created:
5 years ago
by:
Guest
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Script Preparation code:
var obj = { 'a': 1, 'b': 1, 'c': 1, 'd': 1, 'e': 1, 'f': 1, 'g': 1 };
Tests:
for-in
for (var i=10000; i > 0; i--) { for (var key in obj) { console.log(key); } }
Object.keys
for (var i=10000; i > 0; i--) { for (var key of Object.keys(obj)) { console.log(key) } }
Object.entries
for (var i=10000; i > 0; i--) { for (var [key,value] of Object.entries(obj)) { console.log(key) } }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
for-in
Object.keys
Object.entries
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Explanation** The provided JSON represents a JavaScript microbenchmark that compares the performance of three different approaches to iterate over an object's properties: `for-in`, `Object.keys()`, and `Object.entries()`. **Options Compared** 1. **`for-in`**: This method uses the `in` operator to iterate over the object's properties. It returns a string representing the key, which can be used for logging or other purposes. 2. **`Object.keys()`**: This method returns an array of strings representing the object's property keys. In this benchmark, it is used in a traditional `for` loop to iterate over the keys. 3. **`Object.entries()`**: This method returns an array of arrays containing the key-value pairs of the object. It is used in a traditional `for` loop with destructuring assignment (`for (var [key, value] = ...`) to access both the key and value. **Pros and Cons** * `for-in`: Pros: Easy to use, no need for explicit looping or array iteration. Cons: Can be slow because it relies on property enumeration, which may lead to slower performance compared to other methods. * `Object.keys()`: Pros: Fast and efficient way to get an array of keys. Cons: Requires additional overhead for creating the array. * `Object.entries()`: Pros: Offers a convenient way to iterate over key-value pairs simultaneously. Cons: May be slower than using `Object.keys()` or traditional looping due to the additional indirection. **Library and Special JS Features** There are no specific libraries used in this benchmark. However, the use of JavaScript features like `for...of` loops (used in `Object.entries()`) is noteworthy. These loops provide a concise way to iterate over arrays and other iterable objects, but they may not be supported by older browsers. **Other Alternatives** Other alternatives for iterating over an object's properties include: * Using `forEach()` method on the object. * Using `for...in` with a `switch` statement to handle property values. * Using `reduce()` method or other aggregation functions to process object properties. Keep in mind that each of these alternatives has its own trade-offs and performance characteristics, which may be different from those discussed above.
Related benchmarks:
For in vs For of
for-in vs Object.keys()
Object entries vs forin
for-in vs Object.entires
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