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in vs hasOwn
(version: 0)
Object lookup performance Comparing performance of: in vs hasOwn
Comparing performance of:
in vs hasOwn
Created:
one year ago
by:
Guest
Jump to the latest result
Script Preparation code:
var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
Tests:
in
'd' in obj;
hasOwn
Object.hasOwn(obj, 'd');
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
in
hasOwn
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
10 months ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Firefox/140.0
Browser/OS:
Firefox 140 on Windows
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Test name
Executions per second
in
934940544.0 Ops/sec
hasOwn
783551552.0 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to help explain the JavaScript microbenchmark provided by MeasureThat.net. **Benchmark Overview** The benchmark compares the performance of two different ways to check if an object has a property: using the `in` operator and using the `hasOwn()` method. The test is designed to measure which approach is faster, but more importantly, it helps identify any potential performance bottlenecks in JavaScript code. **Options Compared** The benchmark compares the following two options: 1. **`d in obj`**: This uses the `in` operator to check if the object `obj` has a property named `d`. The `in` operator checks for both the presence and value of the property. 2. **`Object.hasOwn(obj, 'd')`**: This uses the `hasOwn()` method, which is part of the ECMAScript Object API, to check if the object `obj` has a property named `d`. **Pros and Cons** Here are some pros and cons of each approach: * **`in` operator:** + Pros: - Widely supported across browsers - Can be faster for simple checks (less overhead) + Cons: - May not work correctly with non-enumerable properties or symbols - May return `true` if the property is a getter or setter function (not what you want in this case) * **`hasOwn()` method:** + Pros: - More explicit and readable - Avoids potential issues with non-enumerable properties or symbols + Cons: - May be slower due to the extra overhead of calling a function **Library and Purpose** The `Object.hasOwn()` method is part of the ECMAScript Object API, which provides a standardized way for objects to interact. This method checks if an object has a property with the given name. **Special JS Features or Syntax** None mentioned in this benchmark. **Other Alternatives** There are other ways to check if an object has a property, such as: * Using `Object.prototype.hasOwnProperty()` ( deprecated and removed from ECMAScript 5) * Using a simple `if` statement: `if ('d' in obj) { ... }` * Using a regex: `/^d$/` However, these alternatives are not included in this benchmark. **Benchmark Preparation Code** The preparation code for the benchmark creates an object `obj` with five properties (`a`, `b`, `c`, `d`, and `e`). The script to be measured is then executed using the `in` operator or the `hasOwn()` method, depending on the test case. **Individual Test Cases** Each test case executes a single line of code: `'d' in obj;` or `Object.hasOwn(obj, 'd');`. These lines are designed to check if the object `obj` has a property named `d`. The benchmark results show the performance metrics for each test case, including the number of executions per second. I hope this explanation helps you understand what's happening in this JavaScript microbenchmark!
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