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undefined vs. typeof vs. in vs. hasOwnProperty my 4
(version: 0)
Object lookup performance
Comparing performance of:
ue vs aue vs eu vs eau
Created:
6 years ago
by:
Guest
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Script Preparation code:
var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
Tests:
ue
undefined !== obj.d;
aue
'undefined' !== typeof obj.d;
eu
undefined !== obj.xxxd;
eau
'undefined' !== typeof obj.xxxd;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
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Test case name
Result
ue
aue
eu
eau
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 JSON and explain what's being tested, compared, and some of the considerations. **Benchmark Definition** The benchmark is designed to test object lookup performance using four different methods: 1. `undefined` 2. `typeof` with a string literal 3. `in` operator 4. `hasOwnProperty` These methods are all used to access properties on an object (`obj`) that contains 5 properties: `a`, `b`, `c`, `d`, and `e`. The benchmark is interested in the lookup performance of each method. **Options Compared** Here's a brief explanation of what's being compared: * `undefined`: Using the value `undefined` to access an object property. This is likely being used to test if the object has the property, but since it's set to `undefined`, this will always return false. * `typeof obj.d`: Using the `typeof` operator to check the type of `obj.d`. Since `d` is a string, this will return `'string'`. * `in`: Using the `in` operator to check if the object has the property. This operator returns a boolean value indicating whether the property exists. * `hasOwnProperty`: Using the `hasOwnProperty` method on the object to check if it owns the property. This method returns a boolean value indicating whether the property is an own property of the object. **Pros and Cons** Here are some pros and cons for each approach: * `undefined`: Pros: None. Cons: The lookup will always return false, which may not accurately represent real-world usage. * `typeof obj.d`: Pros: Returns a string indicating the type of `obj.d`. Cons: May have performance overhead due to the type check. * `in`: Pros: Fast and efficient for checking property existence. Cons: May not be as precise as other methods since it only checks if the property exists, not its value. * `hasOwnProperty`: Pros: Returns a boolean indicating whether the property is an own property of the object. Cons: May have performance overhead due to the method call. **Library Usage** There are no libraries explicitly mentioned in this benchmark definition. However, the use of `typeof` and `in` operators suggests that JavaScript's built-in type system and operator overloads are being utilized. **Special JS Features/Syntax** The benchmark does not specifically test any special JavaScript features or syntax beyond what is already covered by the `typeof`, `in`, and `hasOwnProperty` methods. However, it does utilize some advanced concepts like object literals and property access. **Alternatives** Other alternatives for testing object lookup performance might include: * Using a different data structure, such as an array or set. * Testing the performance of multiple property accesses in a row. * Using a different language or platform to test compatibility with this benchmark. Keep in mind that these alternatives would require significant changes to the benchmark definition and setup.
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