Question

is there a way to check the type of an object in javascript against a custom type? I probably worded that wrong so let me show you what i’m wanting to do:

if(typeof value == "MyClassType")
     console.log(true);

can you do this with typeof, instanceof, or anything like that? I’m wanting to throw an error if the user provides a value that’s not a class i’m expecting.

Answer 1

Use the instanceof operator:

if (!(value instanceof MyClassType)) {
    throw new Error("expected object of type 'MyClassType'");
}

Documentation: msdn, mdn