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typeof vs instanceof vs null
(version: 0)
Comparing performance of:
typeof vs instanceof vs null
Created:
6 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var f = () => {};
Tests:
typeof
typeof f === 'function'
instanceof
f instanceof Function
null
f === null
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
typeof
instanceof
null
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down the benchmark definition and test cases for you. **Benchmark Definition** The provided JSON defines a benchmarking scenario, which is used to compare the performance of three different approaches: 1. `typeof f === 'function'` 2. `f instanceof Function` 3. `f === null` These expressions check the type or identity of an object `f`. The goal is to measure which approach is faster. **Options Compared** The three options compared are: * `typeof f === 'function'`: This checks if `f` is a function using the `typeof` operator, which returns the type of a variable. In this case, since `f` is an anonymous function expression, it will return `'function'`. * `f instanceof Function`: This checks if `f` is an instance of the `Function` constructor, which tests if an object is constructed as a function. * `f === null`: This simply checks if `f` is equal to `null`, which compares the two values using the equality operator (`===`). **Pros and Cons** Here's a brief summary: 1. `typeof f === 'function'`: * Pros: Simple, easy to read, and maintain. * Cons: May not be as efficient for large objects or complex types, since it uses a string literal comparison. 2. `f instanceof Function`: * Pros: More accurate than `typeof`, especially for constructors like `Function`. * Cons: May be slower due to the constructor lookup process. 3. `f === null`: * Pros: Fast and simple. * Cons: Only checks for exact equality, not type or identity. **Library Use** None of the provided test cases use a library explicitly. **Special JS Features or Syntax** There's one notable feature in this benchmark: 1. **Anonymous Function Expressions**: The `var f = () => {};` syntax is used to create an anonymous function expression, which is not immediately obvious to everyone. This syntax was introduced in ECMAScript 2015 (ES6) as a new way of defining functions without declaring their name. **Other Alternatives** If the developers behind MeasureThat.net wanted to include additional test cases or variations, they might consider: * Using different data types or values for `f` (e.g., numbers, strings, objects). * Adding more complex expressions or conditions to check. * Incorporating other operators or functions from JavaScript, such as `in`, `hasOwnProperty`, or `String.prototype.includes`. * Considering the impact of various browser optimizations or engine-specific behaviors on performance. Overall, this benchmark provides a clear and concise way to compare the performance of these three approaches in measuring object type or identity.
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