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undefined vs. hasOwnProperty
(version: 0)
Object lookup performance
Comparing performance of:
undefined vs hasOwnProperty
Created:
7 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
Tests:
undefined
if(obj.d){};
hasOwnProperty
if(obj.hasOwnProperty('d')){}
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
undefined
hasOwnProperty
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down the explanation for you. **Benchmark Definition** The provided JSON represents a JavaScript microbenchmark named "undefined vs. hasOwnProperty" that tests object lookup performance. **Options Compared** Two options are compared: 1. `if(obj.d){};`: This option uses the property access syntax with a literal value (`obj.d`). It checks if the property `d` exists in the object, but it doesn't check its type or value. 2. `if(obj.hasOwnProperty('d')){}`: This option uses the `hasOwnProperty()` method of the object, which returns a boolean indicating whether the specified property is an own property (i.e., not inherited from the prototype chain) and has a value. **Pros and Cons** * Using literal values (`obj.d`) has some pros: + It's straightforward and easy to read. + It doesn't rely on the object's prototype chain or its `hasOwnProperty()` method. * However, using literal values also has some cons: + If the object's prototype chain contains other properties with the same name as `d`, this option may match those properties instead of checking for the exact property `d`. + This approach doesn't take into account the possibility that `obj.d` might be a symbolic property. * Using `hasOwnProperty()` has some pros: + It's more accurate and reliable than using literal values, as it checks the object's own properties without relying on its prototype chain. + It's also more expressive, as it explicitly indicates that you're checking for an own property. * However, using `hasOwnProperty()` also has some cons: + It may be slightly slower than using literal values, since it involves a method call and checks the object's own properties. + Some older browsers might not support this method. **Library Usage** There is no explicit library usage in this benchmark definition. However, if we look at the individual test cases, we can see that one of them uses the `hasOwnProperty()` method: ```javascript if(obj.hasOwnProperty('d')){} ``` This suggests that the implementation of `hasOwnProperty()` might be optimized or implemented differently for performance reasons. **Special JS Features** There are no special JavaScript features mentioned in this benchmark definition. The code is written in standard JavaScript syntax and doesn't use any advanced features like async/await, promises, generators, or functional programming constructs. Now, regarding alternatives to these approaches: * If you want to test object lookup performance with a more accurate and reliable method, you could consider using the `in` operator instead of `hasOwnProperty()`. This operator checks if a property exists in the object's own properties and its prototype chain. ```javascript if('d' in obj){} ``` * Alternatively, you could use a library like `fast-assert` or `deep-object` to implement a custom lookup function that takes into account the object's own properties and its prototype chain. Keep in mind that these alternatives might affect performance, readability, or maintainability of your benchmark code.
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