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Check object. typeof vs constructor + null check
(version: 0)
Difference between typeof(a => {}) === 'object' and (a => {}).constructor === Object
Comparing performance of:
typeof vs constructor
Created:
3 years ago
by:
Guest
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Script Preparation code:
var obj = {a: 'val1'};
Tests:
typeof
typeof(obj) === 'object'
constructor
obj && obj.constructor === Object
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
typeof
constructor
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to explain the provided benchmark and its test cases. **Benchmark Definition** The benchmark definition is a JSON object that defines the overall characteristics of the benchmark. In this case, it specifies: * The name of the benchmark: "Check object. typeof vs constructor + null check" * A brief description of the benchmark: "Difference between typeof(a => {}) === 'object' and (a => {}).constructor === Object" **Script Preparation Code** The script preparation code is a JavaScript snippet that initializes the test data before running the benchmark. In this case, it creates an object `obj` with a single property `a` containing the string `'val1'`. **Html Preparation Code** There is no HTML preparation code specified in this benchmark. **Individual Test Cases** The benchmark consists of two individual test cases: 1. **Test Case 1: "typeof"** This test case uses the `typeof` operator to check if `obj` is an object. The benchmark definition is `typeof(obj) === 'object'`. Pros: * Simple and concise * Easy to understand Cons: * May not work correctly with non-standard objects or arrays * Does not account for null or undefined values **Test Case 2: "constructor"** This test case uses the `constructor` property of `obj` to check if it is an object. The benchmark definition is `(a => {}).constructor === Object`. Pros: * More accurate than using `typeof`, as it accounts for non-standard objects and arrays * Handles null or undefined values correctly Cons: * Less concise and more complex than the `typeof` test case * May not be as intuitive to understand **Library: Function Expression** In both test cases, a function expression is used to create an anonymous object `obj`. The purpose of this library is to provide a way to create objects dynamically using a concise syntax. **Special JS Feature/Syntax: No special features or syntax are mentioned in the benchmark definition.** **Other Alternatives** If you wanted to run this benchmark, you would need to: * Set up a test environment with JavaScript and a web browser * Modify the script preparation code to accommodate your specific use case * Run the benchmark using a tool such as MeasureThat.net or a custom implementation In conclusion, the "typeof" test case is simple but may not work correctly in all scenarios. The "constructor" test case is more accurate but less concise and potentially more complex. The function expression library used in both test cases provides a convenient way to create objects dynamically.
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