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Regex type checking comparison
(version: 0)
Comparing performance of:
instanceof vs test property
Created:
3 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var regex = /[a-z]/i;
Tests:
instanceof
regex instanceof RegExp
test property
!!regex.test
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
instanceof
test property
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36
Browser/OS:
Chrome 129 on Windows
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=557456" width="100%" height="500px"></iframe>
test property
19.6M/s
instanceof
7.6M/s
View exact numbers
Test name
Executions per second
✓
test property
19,638,160 Ops/sec
instanceof
7,587,502 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of MeasureThat.net and understand what's being tested in this benchmark. **What is tested?** The provided JSON represents a JavaScript microbenchmark that compares two different approaches to check if a variable `regex` is an instance of the `RegExp` class. There are two test cases: 1. **"instanceof"**: This test case checks if `regex instanceof RegExp`. 2. **"test property"**: This test case checks if the `test` property of the `regex` object returns true. **Options compared** The benchmark compares the performance of two approaches to check if a variable is an instance of the `RegExp` class: 1. **Using `instanceof` operator**: This approach uses the `instanceof` operator (`regex instanceof RegExp`) to check if `regex` is an instance of `RegExp`. 2. **Using `test` property**: This approach checks if the `test` property of the `regex` object returns true. **Pros and cons of each approach** * **Using `instanceof` operator**: + Pros: Simple, straightforward, and widely supported. + Cons: Can be slower than using a method like `test()` on non-RegExp values, as it requires a more complex type check. * **Using `test` property**: + Pros: Can be faster for non-RegExp values, as it only checks if the value has a `test()` method without needing to perform a full instance check. + Cons: May return unexpected results if the `test` property is not defined or is set to an incorrect value. Additionally, this approach may not work correctly on all browsers or environments. **Library usage** There is no explicit library mentioned in the benchmark definition or test cases. However, it's worth noting that the use of the `RegExp` class and its properties like `test()` might rely on built-in JavaScript functionality. **Special JS feature or syntax** The benchmark does not explicitly mention any special JavaScript features or syntax. The use of `instanceof`, `RegExp`, and `test` property is standard JavaScript syntax. **Other alternatives** If you're interested in exploring alternative approaches to check if a variable is an instance of the `RegExp` class, here are a few options: 1. **Using `constructor.name`**: In modern browsers (e.g., Chrome 129), you can use `regex.constructor.name === 'RegExp'` to check if `regex` is an instance of `RegExp`. 2. **Using a library like Lodash**_: If you prefer a more functional approach, you could use the `isRegExp` function from Lodash _.isRegExp(regex)` to check if `regex` is an instance of `RegExp`. Keep in mind that these alternatives might have different performance characteristics or behave differently across browsers and environments. I hope this explanation helps!
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