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undefined vs. typeof vs. in vs. hasOwnProperty vs. Optional chaining
(version: 0)
Object lookup performance
Comparing performance of:
undefined vs typeof vs in vs hasOwnProperty vs bool vs ?.
Created:
4 years ago
by:
Guest
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Script Preparation code:
var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
Tests:
undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;
?.
obj?.d
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (6)
Previous results
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Test case name
Result
undefined
typeof
in
hasOwnProperty
bool
?.
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks! **What is being tested?** MeasureThat.net is testing the performance of different approaches to access and compare properties of an object in a JavaScript environment. **Options compared:** The benchmark compares six different options: 1. `undefined` vs. literal value (e.g., `"d"`) 2. `typeof` vs. literal value (e.g., `'d'`) 3. `in` vs. property existence check 4. `hasOwnProperty` vs. property existence check 5. Optional chaining (`?.`) vs. explicit property access 6. Boolean negation (`!!`) vs. simple property access **Pros and Cons of each approach:** 1. **Undefined**: This approach uses a literal value to represent the non-existent property. Pros: Simple, easy to understand. Cons: May lead to performance issues due to unnecessary type checking. 2. **typeof**: This approach uses the `typeof` operator to check if a variable is an object with a `d` property. Pros: More robust than `undefined`, but still slower than some other approaches. Cons: May not work as expected for non-object values. 3. **in**: This approach uses the `in` operator to check if a variable is present in an object. Pros: Fast, simple, and widely supported. Cons: May lead to false positives or negatives due to object property behavior. 4. **hasOwnProperty**: Similar to `in`, but only checks for direct properties of the object. Pros: More accurate than `in` for objects with nested properties. Cons: Slower than `in`. 5. **Optional chaining (?.)**: This approach uses the optional chaining operator (`?.`) to access a property without throwing an error if it doesn't exist. Pros: Fast, safe, and modern. Cons: Requires ES6+ support. 6. **Boolean negation**: This approach uses double exclamation marks (`!!`) to negate a boolean value before accessing a property. Pros: Simple, easy to understand. Cons: May lead to performance issues due to unnecessary type checking. **Library usage:** The benchmark does not explicitly use any libraries, but it may be relying on some built-in JavaScript features or behaviors that could be considered part of the language specification (e.g., `in`, `hasOwnProperty`). **Special JS feature/syntax:** Optional chaining (`?.`) is a relatively new feature introduced in ES6+ syntax. It allows safe navigation through objects without throwing errors. Other alternatives: * **Bracket notation**: Instead of using `in` or `hasOwnProperty`, you could use bracket notation (`obj['d']`) to access properties dynamically. * **Property access with `[]`**: Similar to bracket notation, you could use property access with square brackets (`obj['d']`) for dynamic property access. Keep in mind that these alternatives may have different performance characteristics and are not necessarily equivalent to the approaches tested in this benchmark.
Related benchmarks:
undefined vs. typeof vs. in vs. hasOwnProperty
undefined vs. hasOwnProperty
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undefined vs. typeof vs. in vs. hasOwnProperty big object
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