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Check object. typeof vs constructor
(version: 0)
Difference between typeof(a => {}) === 'object' and (a => {}).constructor === Object
Comparing performance of:
typeof vs constructor
Created:
3 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var obj = {a: 'val1'};
Tests:
typeof
typeof(obj) === 'object'
constructor
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:
Run details:
(Test run date:
11 months ago
)
User agent:
Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0
Browser/OS:
Firefox 142 on Linux
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=615969" width="100%" height="500px"></iframe>
constructor
1560.3M/s
typeof
1513.5M/s
View exact numbers
Test name
Executions per second
✓
constructor
1,560,321,408 Ops/sec
typeof
1,513,487,488 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the benchmark and explain what's being tested. **Benchmark Overview** The MeasureThat.net benchmark measures the performance difference between two approaches to checking if an object is of type `object` in JavaScript: 1. Using the `typeof` operator (`typeof obj === 'object'`) 2. Using the `constructor` property of the object (`obj.constructor === Object`) **Options Compared** Two options are being compared: 1. **Using `typeof`**: This method uses the built-in `typeof` operator to check if an object is of type `object`. 2. **Using `constructor`**: This method checks if the constructor of an object is equal to the global `Object` constructor. **Pros and Cons** Here's a brief analysis of each approach: * **Using `typeof`**: + Pros: Simple, widely supported, and efficient. + Cons: Can return incorrect results for certain types of objects (e.g., arrays) or when used with `null`. * **Using `constructor`**: + Pros: More accurate than `typeof`, as it checks the actual constructor function, not just its name. + Cons: Requires accessing the object's properties and may be slower due to the additional lookup. **Library Usage** In this benchmark, no libraries are explicitly mentioned. However, the use of the global `Object` constructor implies that JavaScript is being executed in a context where this object is available and can be used as expected. **Special JS Features/Syntax** None of the special features or syntax (e.g., async/await, arrow functions, classes) are being utilized in this benchmark. The code is simple and straightforward. **Other Alternatives** If you're looking for alternative approaches to checking if an object is of type `object`, consider: * **Using `instanceof`**: This method checks if an object is an instance of a specific constructor function (e.g., `Array` or `Object`). It's more precise than `typeof` but may not work with all types. * **Using `isPrototypeOf()`**: This method checks if one object is in the prototype chain of another. It can be useful for certain use cases, such as checking if an object has a specific property. Keep in mind that these alternatives might have different performance characteristics or trade-offs compared to the original approaches being tested in this benchmark.
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Check function. typeof vs constructor + null check
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