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undefined vs hasOwnProperty
(version: 0)
Object lookup performance
Comparing performance of:
undefined vs hasOwnProperty vs bool
Created:
5 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
undefined !== obj['d'];
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
undefined
hasOwnProperty
bool
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what is being tested. **Benchmark Definition** The benchmark is defined as an object with four properties: `Name`, `Description`, `Script Preparation Code`, and `Html Preparation Code`. In this case, the description is "Object lookup performance". **Options Compared** The script preparation code defines three different ways to look up a property in an object: 1. Using the `undefined` keyword: `var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 }; undefined !== obj['d'];` 2. Using the `hasOwnProperty()` method: `obj.hasOwnProperty('d');` 3. Using the double exclamation mark (`!!`) operator: `!! obj.d;` The description suggests that these three approaches are being compared in terms of performance. **Pros and Cons** * **Using `undefined`**: This approach is simple and straightforward. However, it may not be as efficient as other methods, as the JavaScript engine needs to perform a property lookup on the `obj` object. * **Using `hasOwnProperty()`**: This method is more efficient than using `undefined`, as it uses a native method that is optimized by the browser's engine. It also provides additional information about whether the property exists or not. * **Using `!!` operator**: The double exclamation mark operator performs a type coercion and returns a boolean value. While this may seem like an unusual approach, it can be faster than using `hasOwnProperty()` for some use cases. **Library** None of the provided benchmark definitions rely on external libraries. However, the benchmark uses the `!!` operator, which is a part of the JavaScript language standard. **Special JS Features/Syntax** There are no special JavaScript features or syntax used in this benchmark. The code snippets are straightforward and easy to understand. **Other Alternatives** * To compare the performance of different object lookup methods, you could also use other approaches, such as: + Using `in` operator: `var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 }; 'd' in obj;` + Using the `typeof` operator with the `object` type: `var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 }; typeof obj['d'] === 'object';` + Using a closure to create a function that checks if a property exists on an object. Keep in mind that these alternatives may introduce additional overhead or complexity compared to the original approach.
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