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undefined vs. typeof vs. in vs. hasOwnProperty my3
(version: 0)
Object lookup performance
Comparing performance of:
ue vs aue vs eu vs eau
Created:
6 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:
ue
undefined !== obj.d;
aue
'undefined' !== typeof obj.d;
eu
obj.d === undefined;
eau
typeof obj.d === 'undefined';
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:
No previous run results
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Overview** The provided JSON represents a JavaScript microbenchmark test case created using MeasureThat.net. The test case measures the performance of different operators (undefined, typeof, in, and hasOwnProperty) when used with the variable `obj.d`, which is an object property. **Operators Being Compared** 1. **`!=` (not equal to)**: This operator checks if two values are not equal. 2. **`typeof obj.d === 'undefined'`:** This expression checks if the type of `obj.d` is undefined. 3. **`in`**: This operator checks if a property exists in an object. 4. **`hasOwnProperty(obj, 'd')`**: This function checks if `obj` has a property named `'d'`. **Pros and Cons of Each Approach** 1. **`!=` (not equal to)`: * Pros: Simple and efficient; works well for most cases. * Cons: May not work correctly with some edge cases, such as NaN or boolean values. 2. **`typeof obj.d === 'undefined'`:** * Pros: Works correctly for undefined values; can be useful in certain scenarios where other checks fail. * Cons: May lead to unexpected results if `obj.d` is a function or has a different type. 3. **`in`**: * Pros: Works correctly even if `obj.d` is not defined; reliable when used with objects. * Cons: Can be slower than other approaches, especially for large objects. 4. **`hasOwnProperty(obj, 'd')`**: * Pros: Only checks for the existence of `'d'` in `obj`, reducing unnecessary checks. * Cons: May be slower due to the additional function call. **Library Used** None is explicitly mentioned in the provided JSON. However, the benchmark likely uses JavaScript's built-in object methods and operators. **Special JS Features or Syntax (Not Mentioned)** There are no special JavaScript features or syntax mentioned in the benchmark. The test cases only use standard JavaScript operators and expressions. **Alternatives** Other alternatives for measuring object property existence or checking undefined values include: * Using `Object.prototype.hasOwnProperty.call(obj, 'd')` * Utilizing a library like Lodash's `has` function * Implementing custom logic using JavaScript conditional statements Keep in mind that the choice of alternative may depend on specific use cases and performance requirements.
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undefined vs. typeof vs. in vs. hasOwnProperty
undefined vs. hasOwnProperty
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