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typeof x === 'number' vs isNaN(x) avi
(version: 0)
Comparing performance of:
typeof vs isNaN
Created:
2 years ago
by:
Guest
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Tests:
typeof
typeof Number('5') === 'number'
isNaN
isNaN('5')
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
typeof
isNaN
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to help explain the JavaScript microbenchmark on MeasureThat.net. **Overview of the Benchmark** The benchmark compares two approaches for checking if a value is a number: `typeof x === 'number'` and `isNaN(x)`. The goal is to determine which approach is faster and more efficient. **Options Compared** There are only two options being compared: 1. **`typeof x === 'number'`**: This method checks if the type of the variable `x` is `'number'`. It's a simple and intuitive way to check if a value is a number. 2. **`isNaN(x)`**: This function returns `true` if its argument is not a valid number (NaN = Not a Number). If you know that your variable will always be a number, this can be a faster and more efficient way to check. **Pros and Cons of Each Approach** 1. **`typeof x === 'number'`**: * Pros: Simple and easy to read. * Cons: May not work as expected if `x` is an object with a numeric property (e.g., `{ foo: 5 }`). In this case, the type of `foo` would be `'object'`, but its value is still `'number'`. 2. **`isNaN(x)`**: * Pros: Faster and more efficient, especially for numbers. * Cons: May return incorrect results if `x` is not a number (e.g., NaN or a string representation of a number). **Library Usage** There are no libraries mentioned in the benchmark definition. **Special JavaScript Features/Syntax** None of the test cases use any special JavaScript features or syntax beyond standard ECMAScript. **Other Alternatives** If you need to check if a value is a number, other alternatives could be: * Using a regular expression: `/^[-+]?[0-9]*\.?[0-9]+$/.test(x)`. This method can be slower than `typeof x === 'number'`, but it's more robust and handles non-numeric values correctly. * Checking if the value is an instance of `Number`: `x instanceof Number`. This method is faster than `typeof x === 'number'` for numbers, but may return incorrect results for other numeric types (e.g., BigInt). Keep in mind that these alternatives might not be as straightforward or readable as the original approaches.
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