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instanceof vs typeof vs attribute
(version: 0)
Comparing performance of:
instanceof vs typeof vs typeof no function vs typeof and test attribute vs attribte
Created:
3 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var obj = {a:2};
Tests:
instanceof
obj instanceof Object
typeof
typeof obj === 'object'
typeof no function
typeof obj === 'object' && typeof obj !== 'function'
typeof and test attribute
typeof obj === 'object' && obj.a
attribte
obj.a !== undefined
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
Previous results
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Test case name
Result
instanceof
typeof
typeof no function
typeof and test attribute
attribte
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Overview of the Benchmark** The provided JSON represents a JavaScript microbenchmark that tests the performance of three different approaches to check if an object has a specific property or attribute: `instanceof`, `typeof`, and `attribute` checks. **Options being compared** * `instanceof`: Verifies if an object is an instance of a particular constructor function. In this case, it's checking if the object `obj` is an instance of the `Object` constructor. * `typeof`: Returns the type of an object as a string. For example, `typeof obj` returns `"object"`. * `attribute` check: Verifies if an object has a specific property or attribute. In this case, it's checking if `obj.a` is truthy. **Pros and Cons** * **Instanceof**: This approach can be slower because it involves a constructor function lookup, which can lead to additional overhead. * Pros: + More accurate for some cases (e.g., checking if an object has inherited properties) * Cons: + Slower due to constructor function lookup * **Typeof**: This approach is generally faster because it only checks the type of the object, without involving a constructor function lookup. * Pros: + Faster + More concise * Cons: + Less accurate for some cases (e.g., checking if an object has inherited properties) * **Attribute check**: This approach is generally faster because it only checks the existence of the property or attribute, without involving a type check. * Pros: + Faster + More concise * Cons: + Less accurate for some cases (e.g., checking if an object has inherited properties) **Library and Special JavaScript Features** There is no explicit library mentioned in the benchmark. However, the use of `instanceof` and `typeof` suggests that the benchmark is using built-in JavaScript features. The use of `obj.a` in one of the test cases implies that the object `obj` has a property or attribute named `a`. **Other Alternatives** Some alternative approaches to checking if an object has a specific property or attribute include: * Using a library like Lodash's `hasOwnProperty` or `lodash.isObject` * Using a regex pattern to check for the existence of a property * Using a custom implementation involving a simple loop to iterate over the object's properties However, these alternatives may not be as efficient or concise as using built-in JavaScript features like `instanceof`, `typeof`, and attribute checks. **Benchmark Preparation Code Explanation** The preparation code provided is: ```javascript var obj = {a: 2}; ``` This code creates an object `obj` with a single property `a` containing the value `2`. This object will be used as the test subject for the benchmark.
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