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undefined vs. typeof vs. in vs. hasOwnProperty 1000 items
(version: 0)
Object lookup performance
Comparing performance of:
undefined vs typeof vs in vs hasOwnProperty vs bool
Created:
5 years ago
by:
Guest
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Script Preparation code:
var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
Tests:
undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
Previous results
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Test case name
Result
undefined
typeof
in
hasOwnProperty
bool
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):
Let's break down the provided JSON and benchmark details to understand what is being tested. **Benchmark Definition** The benchmark definition tests the performance of different ways to check if an object property exists or has a specific value. The five test cases are: 1. `undefined !== obj.d;`: checks if `obj.d` is not undefined. 2. `'undefined' !== typeof obj.d;`: checks if `typeof obj.d` (i.e., the type of `obj.d`) is not 'undefined'. 3. `'d' in obj;`: checks if 'd' is a property of `obj`. 4. `obj.hasOwnProperty('d');`: checks if `obj` has a property named 'd' using the `hasOwnProperty` method. 5. `!! obj.d;`: checks if `obj.d` is truthy (i.e., not false, 0, or an empty string). **Options being compared** The benchmark compares the performance of these five test cases across different browsers and devices. **Pros and cons of each approach:** 1. **`undefined !== obj.d;`**: This approach is simple and straightforward. However, it may have a higher overhead due to the `!==` operator's use. 2. **`'undefined' !== typeof obj.d;`**: This approach uses the `typeof` operator, which can be slower than other methods. Additionally, the comparison involves string literals, which might incur additional overhead. 3. **`'d' in obj;`**: This approach is efficient and straightforward, as it only requires a single operation to check if 'd' exists as a property of `obj`. However, it may not be supported by all browsers. 4. **`obj.hasOwnProperty('d');`**: This approach uses the `hasOwnProperty` method, which can be slower than other methods due to its additional overhead. Additionally, this method only checks for direct properties, whereas `'d' in obj;` checks all properties of `obj`. 5. **`!! obj.d;`**: This approach is a clever trick using the double bang operator (`!!`) to convert `obj.d` to a boolean value. However, it may not be immediately clear what this test case is checking. **Libraries and special JS features** None of these benchmark tests use any specific libraries or special JavaScript features. **Other alternatives** Some alternative approaches for testing object property existence could include: * Using the `in` operator with an array to check if a key exists in a map (e.g., `{ [key]: value }`) * Utilizing modern JavaScript features like `has` on the `Object.prototype` or `Map` objects * Using third-party libraries like Lodash or Jest for their utility functions related to object property existence However, these alternatives are not being tested in this benchmark.
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