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Tyepof vs string casting
(version: 0)
Comparing performance of:
typeof vs casting
Created:
2 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var a = 5;
Tests:
typeof
for(let i =0; i <1000; i++) { const b = typeof a === 'string' }
casting
for(let i =0; i <1000; i++) { const b = `${a}` }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
typeof
casting
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to explain what's being tested in the provided JSON benchmark. **Benchmark Definition:** The benchmark measures the performance difference between two approaches: using the `typeof` operator and string casting (`"${a}"`) to check if `a` is a string. The script preparation code simply assigns a value of 5 to a variable named `a`. **Options compared:** Two options are being compared: 1. **Using the `typeof` operator**: This approach checks if `a` is a string by calling the `typeof` function and comparing its result with `'string'`. The `typeof` function returns a string representing the type of the variable, which can be either `'number'`, `'string'`, `'object'`, or another type depending on the value. 2. **String casting**: This approach uses template literals (introduced in ECMAScript 2015) to concatenate the string representation of `a` with a literal string. The syntax is `${a}`. **Pros and cons:** 1. **Using the `typeof` operator**: * Pros: Easy to read and understand, and it's a standard JavaScript function. * Cons: Can be slower due to the overhead of calling a function, especially for simple type checks. 2. **String casting**: * Pros: Generally faster than using the `typeof` operator because it avoids the function call overhead. It's also more concise and readable. * Cons: Requires ECMAScript 2015 support or later (it was not widely supported until around 2020). Some developers might find it less intuitive due to the use of template literals. **Other considerations:** In modern JavaScript engines, the performance difference between these two approaches is usually negligible. However, if you're targeting older browsers or environments with limited JavaScript capabilities, using string casting might be a better choice. The benchmark also doesn't account for other factors that could affect performance, such as: * Variable scope and hoisting * Function call overhead (e.g., when using functions to wrap the type check) * Optimizations enabled by the browser engine or runtime environment **Library usage:** There are no external libraries used in this benchmark. The only library mentioned is Chrome 118's internal engine, which is not explicitly mentioned but implied as a part of the benchmark framework. **Special JS features or syntax:** The benchmark uses template literals (introduced in ECMAScript 2015) to implement string casting, which requires support for at least ES6. If you're targeting older environments without ES6 support, you'll need to use an alternative implementation.
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