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property check
(version: 0)
Object lookup performance
Comparing performance of:
undefined vs typeof vs in vs hasOwnProperty vs bool vs loose comparison to null
Created:
3 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
obj.d !== undefined;
typeof
typeof obj.d !== 'undefined';
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;
loose comparison to null
obj.d != null
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (6)
Previous results
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Test case name
Result
undefined
typeof
in
hasOwnProperty
bool
loose comparison to null
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 benchmark and its options. **Benchmark Overview** The benchmark is designed to measure the performance of object lookup in JavaScript. It creates an object `obj` with properties `a` to `e`, and then runs multiple test cases that check if property `d` exists using different approaches (e.g., `typeof obj.d === 'undefined'`, `'d' in obj`, etc.). **Options Compared** The benchmark compares six different options for checking if a property is defined: 1. **`obj.d !== undefined`**: This option uses the loose equality operator (`!==`) to check if `obj.d` has a value that is not equal to `undefined`. 2. **`typeof obj.d !== 'undefined'`**: This option uses the `typeof` operator to get the type of `obj.d` and then checks if it's not equal to `'undefined'`. 3. **`'d' in obj`**: This option uses the `in` operator to check if the property `'d'` exists in the object. 4. **`obj.hasOwnProperty('d')`**: This option uses the `hasOwnProperty` method of objects to check if the property `'d'` is owned by the object. 5. **`!! obj.d`**: This option uses a boolean cast (`!!`) to convert `obj.d` to a boolean value, which will be `true` for truthy values and `false` for falsy values. 6. **`obj.d != null`**: This option uses a loose comparison operator (`!=`) to check if `obj.d` is not equal to `null`. **Pros and Cons of Each Approach** Here's a brief summary of the pros and cons of each approach: * **`obj.d !== undefined`**: Fastest, but may trigger unnecessary checks on other properties. + Pros: Simple, fast + Cons: May be inefficient if `obj.d` is not defined * **`typeof obj.d !== 'undefined'`**: Slightly slower than the first option, but provides more type information. + Pros: More informative result, slightly faster than loose equality + Cons: Slower than simple equality checks * **`'d' in obj`**: Relatively fast and easy to read, but may not be as efficient as other options. + Pros: Simple, readable + Cons: May not be as fast as other options * **`obj.hasOwnProperty('d')`**: Slightly slower than `in` operator, but provides more context about property ownership. + Pros: More informative result, slightly faster than `in` operator + Cons: Slower than simple equality checks * **`!! obj.d`**: Fast and easy to read, but may not provide useful information if `obj.d` is falsy. + Pros: Simple, fast + Cons: May not be informative for falsy values * **`obj.d != null`**: Slowest option, but provides a simple way to check for null or undefined values. + Pros: Simple, easy to read + Cons: Slower than other options **Other Considerations** The benchmark does not consider the following factors: * Array lookup performance (if `obj` were an array instead of an object) * Object property enumeration performance (e.g., using `Object.keys()` or `for...in`) * Property existence checks on arrays or sets * Cache behavior for repeated runs **Alternatives** If you're interested in exploring alternative benchmarks, you might consider: * Measuring the performance of different approaches to array lookup or enumeration. * Comparing the performance of various data structures (e.g., objects, arrays, sets) for different use cases. * Investigating the impact of caching on repeated benchmark runs. Keep in mind that these alternatives would require modifying the benchmark script and running new tests.
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