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JS: Null vs Undefined
(version: 0)
Comparing performance of:
null === null vs typeof undefined === "undefined"
Created:
4 years ago
by:
Guest
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Tests:
null === null
null === null
typeof undefined === "undefined"
typeof undefined === "undefined"
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
null === null
typeof undefined === "undefined"
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down what's being tested in this JavaScript microbenchmark. **Benchmark Purpose** The goal of this benchmark is to compare the performance of two seemingly equivalent expressions: `null === null` and `typeof undefined === "undefined"`. The benchmark measures which approach is faster, as it can impact the performance of certain parts of the codebase. **Options Compared** There are only two options being compared: 1. **Null Coalescing Operator (`??`)**: Not explicitly mentioned in this benchmark, but implied by the presence of `typeof undefined === "undefined"`. 2. **Equality Check (`===`)**: Using `null === null`. **Pros and Cons** ### Equality Check (`===`) Pros: * Simple and widely supported. * Intuitive to understand. Cons: * May involve a more expensive operation, such as dereferencing the `null` object, which can lead to performance issues in certain situations. ### Null Coalescing Operator (`??`) Pros: * Can be a more efficient way to perform comparisons, especially when working with `undefined` or `null`. * Supports chaining, making it easier to write more expressive code. Cons: * Less intuitive for beginners, as the syntax is not immediately clear. * Not all browsers support this operator (only from ECMAScript 2020+). **Special Consideration** The benchmark uses a special JavaScript feature: the `typeof` operator with a string literal `"undefined"`. This allows testing whether the `typeof` operator is able to provide the correct result for this specific case. If the result was incorrect, it could indicate a bug or misbehavior in the JavaScript engine. **Other Alternatives** Other alternatives to compare performance could include: 1. **Using `null` with a primitive value**: Compare performance of `null === 0`, `null === true`, etc. 2. **Comparing against an array**: Compare performance of `[] === []`, `[].push(0) === [], [] === []`, etc. 3. **Comparing with different data types**: Compare performance of `null === undefined`, `null === null` (the current benchmark), or other combinations. Keep in mind that each alternative will test a specific aspect of JavaScript's behavior and might not be directly comparable to the current benchmark.
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