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Testing for false vs === undefined vs hasOwnProperty vs in for undefined member
(version: 0)
Is there a performance benefit to replacing === undefined with a logical test?
Comparing performance of:
test truth vs test undefined vs test hasOwnProperty vs test in === vs test in !
Created:
3 years ago
by:
Guest
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Tests:
test truth
var n = {}; while(true) { if(!n.foo) break; }
test undefined
var n = {}; while(true) { if(n.foo===undefined) break; }
test hasOwnProperty
var n = {}; while(true) { if(!n.hasOwnProperty('foo')) break; }
test in ===
var n = {}; while(true) { if('foo' in n === false) break; }
test in !
var n = {}; while(true) { if(!('foo' in n)) break; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
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Test case name
Result
test truth
test undefined
test hasOwnProperty
test in ===
test in !
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.1:latest
, generated one year ago):
Let's dive into the benchmarking test case. **What is being tested?** The test case is evaluating the performance of different ways to check if an object has a specific property in JavaScript. **Test cases:** There are five test cases: 1. `test truth`: Checking if `n.foo` exists without using any special syntax or libraries. 2. `test undefined`: Using the triple equals (`===`) operator to check if `n.foo` is strictly equal to `undefined`. 3. `test hasOwnProperty`: Using the `hasOwnProperty()` method on the object `n` to check if it has a property named `'foo'`. 4. `test in ===`: Using the `in` operator with a truthy value (`=== false`) to check if `'foo'` is a property of the object `n`. 5. `test in !`: Similar to the previous test, but using a falsy value (`!`) instead of a truthy one. **Libraries and special features:** None are used in this test case. **Options being compared:** The test cases compare the performance of different ways to check if an object has a specific property: 1. `n.foo` ( simple existence check) 2. `n.foo === undefined` (checking for strict equality with `undefined`) 3. `n.hasOwnProperty('foo')` (using the `hasOwnProperty()` method) 4. `'foo' in n === false` and `!('foo' in n)` (using the `in` operator with a truthy or falsy value) **Pros and cons:** * `n.foo`: Simple and easy to read, but may be slower than other methods. * `n.foo === undefined`: Strictly checks for equality with `undefined`, but may not work correctly in some edge cases (e.g., when the property exists but has a value of `undefined`). * `n.hasOwnProperty('foo')`: Returns `true` if the property exists, regardless of its value. This is a good choice if you need to check for existence without considering the value. * `'foo' in n === false` and `!('foo' in n)`: These methods use the `in` operator with a truthy or falsy value to check for existence. They are generally faster than using `hasOwnProperty()` but may be less readable. **Other considerations:** * When working with objects, it's essential to consider whether you need to check for strict equality (`===`) or just existence (using the `in` operator). * If performance is critical, using the `in` operator with a truthy value might be a good choice. * The test case results suggest that the `test in !` approach is the fastest on Chrome 108. **Alternatives:** Other ways to check for object property existence include: 1. Using the `hasOwnProperty()` method (as shown in this test case). 2. Using the `in` operator with a truthy value (e.g., `'foo' in n === false` or `!('foo' in n)`). 3. Checking if the property is present in an object literal using the syntax `obj.prop === undefined`. 4. Utilizing libraries like Lodash, which provides a more comprehensive set of utility functions for working with objects. Feel free to ask follow-up questions if you need further clarification!
Related benchmarks:
Testing for false vs === undefined for undefined member
Testing for false vs === undefined vs hasOwnProperty for undefined member
Testing for false vs === undefined vs hasOwnProperty for undefined member
Testing for false vs === undefined vs hasOwnProperty for undefined member 3
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