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typof vs null
(version: 0)
Comparing performance of:
typoef vs null vs typof neg vs null neg
Created:
9 years ago
by:
Registered User
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Script Preparation code:
obj = {"kl":"jl"};
Tests:
typoef
if(typeof obj["kl"] === "undefined") var n = 2;
null
if(obj["kl"]) var n = 3;
typof neg
if(typeof obj["ka"] === "undefined") var n = 2;
null neg
if(obj["ka"]) var n = 3;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
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Test case name
Result
typoef
null
typof neg
null neg
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Explanation** The provided JSON represents a JavaScript microbenchmark that tests the performance of different approaches to check for null or undefined values in an object. **Script Preparation Code** The script preparation code `obj = {\"kl\":\"jl\"};` creates an object `obj` with a property named "kl" set to the string "jl". **Html Preparation Code** There is no HTML preparation code provided, which means that this benchmark does not test any specific JavaScript feature or syntax related to DOM manipulation. **Individual Test Cases** The benchmark consists of four individual test cases: 1. `typoef`: Tests whether checking for a non-existent property using `typeof obj["kl"] === "undefined"` is slower than checking directly for the null value `obj["kl"] == null`. 2. `null`: Tests whether checking for an existing property using `obj["kl"]` is faster or equally fast as the above test case. 3. `typof neg`: Similar to `typoef`, but with a negative check for non-existence (`typeof obj["ka"] === "undefined"`). 4. `null neg`: Similar to `null`, but with a negative check for existence (`obj["ka"] == null`). **Comparison of Options** The benchmark compares two approaches: 1. **Direct property access**: Checking directly for the value using `obj["kl"]`. 2. **Using typeof and === operators**: Checking for non-existence or equality using `typeof obj["kl"] === "undefined"`. Pros and Cons: * Direct property access is generally faster because it avoids the overhead of type checking. + Pros: More efficient, less CPU usage. + Cons: May lead to runtime errors if the property doesn't exist. * Using typeof and === operators checks for non-existence or equality in a more explicit way. + Pros: Reduces runtime errors, provides better feedback on why a test failed. + Cons: Slower due to type checking overhead. **Other Considerations** The benchmark also considers the impact of using `== null` instead of just `==`. This check is only necessary if you're checking for `null` explicitly. In modern JavaScript, you can simply use `===` for equality checks. **Libraries and Special Features** There are no specific libraries used in this benchmark. The tests rely on built-in JavaScript features, specifically the `typeof` operator and property access syntax. **Special JS Features or Syntax** The benchmark uses some special syntax: * Property access using square brackets (`obj["kl"]`) * Type checking with `typeof` and `===` If you're interested in learning more about these topics, here are some resources: * [Property Access](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_access) * [Type Checking](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/typeof) **Alternatives** If you're interested in exploring other microbenchmarking tools or approaches, here are some alternatives: 1. **Benchmark.js**: A popular JavaScript benchmarking library that provides more advanced features and flexibility. 2. **js-benchmark**: Another lightweight JavaScript benchmarking library that offers a simple API for creating benchmarks. 3. **Google's Benchmark**: A high-performance benchmarking library developed by Google engineers, which is designed to be fast and efficient. I hope this explanation helps! Let me know if you have any further questions or need clarification on any of the points.
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