How do I check whether a variable is a class constructor or a function? | TypeScript Community | Page 1

river osprey Jun 6, 2023, 1:06 PM

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If I have a variable like this:

const myVar: typeof myClass | (() => string);

How do I check programmatically which it is so I can do either new myVar() if it's a class or myVar() if it's the function?

ivory compass Jun 6, 2023, 1:25 PM

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IIRC there's no simple way to check that at runtime: https://stackoverflow.com/questions/40922531/how-to-check-if-a-javascript-function-is-a-constructor

Stack Overflow

How to check if a Javascript function is a constructor

I noticed not all the Javascript functions are constructors.
var obj = Function.prototype;
console.log(typeof obj === 'function'); //true
obj(); //OK
new obj(); //TypeError: obj is not a constructor

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I would suggest changing myVar, depending on how you want to use it later.

river osprey Jun 6, 2023, 1:31 PM

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I see, thank you

#How do I check whether a variable is a class constructor or a function?