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Has own property
(version: 0)
Check if an object is undefined
Comparing performance of:
Using `in` vs Using `hasOwn()` vs Using `hasOwnProperty()` vs Using `undefined` check
Created:
2 years ago
by:
Registered User
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Script Preparation code:
var o = { path: "a" }
Tests:
Using `in`
!("path" in o)
Using `hasOwn()`
Object.hasOwn(o, "path")
Using `hasOwnProperty()`
o.hasOwnProperty("path")
Using `undefined` check
o.path === undefined
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
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Test case name
Result
Using `in`
Using `hasOwn()`
Using `hasOwnProperty()`
Using `undefined` check
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**What is being tested?** The provided JSON represents a JavaScript microbenchmark on the website MeasureThat.net. The benchmark tests whether an object has a specific property. In this case, the benchmark checks if an object `o` has a property called `"path"`. **Options compared:** There are four options compared: 1. **"Using in"`**: This option uses the `in` operator to check if the property exists in the object. 2. **"Using hasOwn()"**: This option uses the `hasOwn()` method, which is a non-standard way of checking if an object has a specific property. Note that this method is not supported by all browsers and should be used with caution. 3. **"Using hasOwnProperty()"**: This option uses the `hasOwnProperty()` method, which is also a non-standard way of checking if an object has a specific property. Like `hasOwn()`, this method is not supported by all browsers. 4. **"Using undefined check"`: This option checks if the property exists by comparing its value to `undefined`. **Pros and Cons:** 1. **"Using in"`**: This is a widely supported and efficient way of checking if an object has a specific property. It works well in most browsers, including modern ones. * Pros: Fast, widely supported, and easy to use. * Cons: None notable. 2. **"Using hasOwn()"**: While this method may seem convenient, it's not widely supported by browsers. Using `in` instead is recommended. * Pros: None notable. * Cons: Not supported in all browsers. 3. **"Using hasOwnProperty()"**: Similar to `hasOwn()`, this method is not supported by all browsers and should be used with caution. * Pros: None notable. * Cons: Not supported in all browsers. 4. **"Using undefined check"`: This approach can lead to unexpected results if the property exists but is not explicitly defined as a property (e.g., due to inheritance). * Pros: None notable. * Cons: Can lead to incorrect results in certain cases. **Library and purpose:** None of these options use a specific JavaScript library. They are built-in methods or operators. **Special JS features or syntax:** None of the test cases use special JavaScript features or syntax. **Other alternatives:** If you need to check if an object has a property, `in` is usually the best option. However, if you're working with legacy browsers that don't support `in`, you may need to use other methods like `hasOwnProperty()` or implement your own solution.
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