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typeof == vs typeof ===
(version: 0)
Comparing performance of:
== vs ===
Created:
2 years ago
by:
Guest
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Tests:
==
var n = 0; while(true) { n++; if(typeof n == 'number') break; }
===
var n = 0; while(true) { n++; if(typeof n === 'number') break; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
==
===
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down the test cases and explain what's being tested, along with the pros and cons of each approach. **Test Case Explanation** The two test cases are measuring the performance difference between using `typeof` with a strict equality operator (`==`) versus an loose equality operator (`===`). The purpose is to compare how often the browser performs type checking when comparing `n` with `'number'`. **Script Preparation Code and Html Preparation Code** These fields are empty, indicating that no custom code needs to be executed before running the benchmark or rendering the HTML page for this test case. **Test Case 1: `typeof ==`** This test case uses a while loop that increments a variable `n` until it breaks out of the loop when `typeof n == 'number'`. This means that the browser is performing type checking on `n` to determine if it's a number. The loose equality operator (`==`) will also trigger this check, which may not be what the developer intends. **Pros and Cons:** Pros: * Simple to understand and implement * Easy to debug Cons: * May perform unnecessary type checks when using `==` * Can lead to performance issues if the loop is executed frequently **Test Case 2: `typeof ===`** This test case uses the same while loop as before, but with `typeof n === 'number'`. This ensures that the browser performs a strict equality check on `n`, which will only trigger when both `typeof n` and `'number'` are exactly equal. This approach avoids unnecessary type checks. **Pros and Cons:** Pros: * Avoids unnecessary type checks * Ensures strict equality checking Cons: * May be slower due to the additional check * More complex to implement ( requires a deeper understanding of `typeof` behavior) **Library and Special JS Features** None of these test cases use any external libraries or special JavaScript features. **Other Considerations** When writing benchmarks, it's essential to consider factors like: * Loop iteration count: How many times the loop is executed? * Variable size and type: Are variables allocated on the stack or heap? * Browser engine and version: Different browsers may optimize type checking differently * Memory pressure: Is memory allocation causing performance issues? **Alternatives** If you want to write similar benchmarks, consider exploring other scenarios like: * Comparing `typeof` with string concatenation vs. using a template literal * Testing the performance of different comparison operators (e.g., `<`, `>`, `===`) * Measuring the impact of type checking on function call performance When writing benchmarks, remember to keep them concise, focused, and relevant to your specific use case.
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