Benchmark: undefined comparison

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>

Previous results

Test case name	Result
undefined
void 0
length

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months 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

View result in a separate tab

Test name	Executions per second
undefined	1753.1 Ops/sec
void 0	188903.2 Ops/sec
length	285758.2 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

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.

Related benchmarks:

undefined comparison (version: 0)

Comparing performance of: undefined vs void 0 vs length

Created: 8 months ago by: Guest

Jump to the latest result

undefined

void 0

length

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):