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undefined comparison
(version: 0)
Comparing performance of:
undefined vs void 0 vs length
Created:
2 years ago
by:
Guest
Go to the latest result
Tests:
undefined
const test = 'abcdefgh' for(let i=10000; i>0; i--) { if (test[i] === undefined) { } }
void 0
const test = 'abcdefgh' for(let i=10000; i>0; i--) { if (test[i] === void 0) { } }
length
const test = 'abcdefgh' for(let i=10000; i>0; i--) { if (i === test.length) { } }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
undefined
void 0
length
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36
Browser/OS:
Chrome 124 on Mac OS X 10.15.7
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=521871" width="100%" height="500px"></iframe>
length
286K/s
void 0
189K/s
undefined
2K/s
View exact numbers
Test name
Executions per second
✓
length
285,758 Ops/sec
void 0
188,903 Ops/sec
undefined
1,753 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark. **Benchmark Purpose** The benchmark measures the performance of JavaScript engines in comparing three different values: `undefined`, `void 0`, and the length of a string. **Comparison Options** There are two primary options being compared: 1. **`if (test[i] === undefined)`**: This option checks if the value at index `i` in the string `test` is `undefined`. Note that in JavaScript, `undefined` is a primitive value, not an object. 2. **`if (test[i] === void 0)`**: This option checks if the value at index `i` in the string `test` is equal to `void 0`, which is another way of writing `undefined`. The `void` keyword is used to suppress the "useless" warning that occurs when the expression following it evaluates to a value that would be discarded. 3. **`if (i === test.length)`**: This option checks if the index `i` is equal to the length of the string `test`. **Pros and Cons** Here's a brief analysis of each option: * **`if (test[i] === undefined)`**: * Pros: Simple, easy to read. * Cons: May lead to unexpected behavior due to the primitive value nature of `undefined`. * **`if (test[i] === void 0)`**: This is generally considered a better option than the first one. It avoids issues related to primitive values and provides more explicit intent. * **`if (i === test.length)`**: * Pros: More intuitive, as it directly checks for an out-of-bounds condition. * Cons: May not perform well due to the string length calculation. **Library/Function Considerations** There are no libraries or functions being used in this benchmark. The tests only involve JavaScript engine-specific optimizations and features. **Special JS Features/Syntax** None of the test cases utilize any special JavaScript features or syntax beyond what's described above. No ES6+ features, async/await, or other advanced constructs are employed. Now that we've explored the details of the benchmark, let's discuss alternatives: * **Alternative Benchmarking Frameworks**: MeasureThat.net is a specialized framework for measuring JavaScript engine performance. Other frameworks like WebPageTest, Lighthouse, and JSPerf might provide similar functionality with additional features. * **Microbenchmarking Libraries**: For more comprehensive testing, consider using libraries like Micro-Benchmark.js or Benchmark.ch. These tools offer a wider range of features and can be used for various types of performance testing. * **Browser-specific testing**: Depending on the specific use case, you might need to test your application in multiple browsers or environments. MeasureThat.net is geared towards measuring JavaScript engine performance, while browser-specific testing may require additional tools like Selenium WebDriver. In summary, this benchmark tests three different approaches for comparing values in a JavaScript string. Each option has its pros and cons, with the second option (using `void 0`) being generally considered more robust due to its handling of primitive values.
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