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instanceof vs typeof vs fast typeof object2
(version: 0)
Comparing performance of:
instanceof vs typeof vs typeof object charAt vs typeof object [0] vs typeof object startsWith
Created:
4 years ago
by:
Guest
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Script Preparation code:
var obj = {a:2};
Tests:
instanceof
obj instanceof Object
typeof
typeof obj === 'object'
typeof object charAt
(typeof obj).charAt(0) === 'o'
typeof object [0]
(typeof obj)[0] === 'o'
typeof object startsWith
(typeof obj).startsWith('o')
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 object charAt
typeof object [0]
typeof object startsWith
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Overview** The MeasureThat.net benchmark is designed to compare the performance of different approaches for checking if an object is of type `Object`. The benchmark tests four variations: 1. `instanceof Object` 2. `typeof obj === 'object'` 3. `(typeof obj).charAt(0) === 'o'` 4. `(typeof obj)[0] === 'o'` 5. `(typeof obj).startsWith('o')` **Test Case 1: instanceof** This test case checks if the object is an instance of `Object` using the `instanceof` operator. Pros: * Clear and concise syntax * Widely supported by most browsers Cons: * May be slower than other approaches due to the overhead of the `instanceof` check * Does not provide any information about the object's type beyond its class name **Test Case 2: typeof obj === 'object'** This test case checks if the object is of type `Object` using the `typeof` operator with a string literal `'object'`. Pros: * Fast and efficient * Provides information about the object's type beyond its class name (specifically, that it's an object) Cons: * May not work correctly for all objects (e.g., arrays, functions) * The string literal `'object'` is hardcoded, which may lead to issues if the benchmark needs to be updated **Test Case 3: (typeof obj).charAt(0) === 'o'** This test case checks if the object's type starts with `'o'` using a combination of `typeof` and the `.charAt()` method. Pros: * Fast and efficient * Does not require a string literal, making it more flexible than Test Case 2 Cons: * May be slower than other approaches due to the overhead of calling methods on an object * The syntax is less intuitive than other approaches **Test Case 4: (typeof obj)[0] === 'o'** This test case checks if the object's type starts with `'o'` using a combination of `typeof` and array indexing. Pros: * Fast and efficient * Does not require a string literal, making it more flexible than Test Case 2 Cons: * May be slower than other approaches due to the overhead of calling methods on an object * The syntax is less intuitive than other approaches **Test Case 5: (typeof obj).startsWith('o')** This test case checks if the object's type starts with `'o'` using a combination of `typeof` and the `.startsWith()` method. Pros: * Fast and efficient * Does not require a string literal, making it more flexible than Test Case 2 Cons: * May be slower than other approaches due to the overhead of calling methods on an object * The syntax is less intuitive than other approaches **Library Used: None** The benchmark does not use any external libraries. **Special JS Features/Syntax** None mentioned in this explanation. However, it's worth noting that `instanceof` and `typeof` are built-in operators in JavaScript, so they do not rely on any external syntax or features. **Alternatives** Other alternatives for checking if an object is of type `Object` include: * Using a function like `isPrototypeOf()` or `constructor.name` * Using a library like `lodash.isPlainObject()` However, these approaches may be slower or more complex than the methods tested in this benchmark.
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