Is there a way to do method overloading in TypeScript?

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According to the specification, TypeScript does support method overloading, but it’s quite awkward and includes a lot of manual work checking types of parameters. I think it’s mostly because the closest you can get to method overloading in plain JavaScript includes that checking too and TypeScript tries to not modify actual method bodies to avoid any unnecessary runtime performance cost.

If I understand it correctly, you have to first write a method declaration for each of the overloads and then one method implementation that checks its arguments to decide which overload was called. The signature of the implementation has to be compatible with all of the overloads.

class TestClass {
    someMethod(stringParameter: string): void;
    someMethod(numberParameter: number, stringParameter: string): void;

    someMethod(stringOrNumberParameter: any, stringParameter?: string): void {
        if (stringOrNumberParameter && typeof stringOrNumberParameter == "number")
            alert("Variant #2: numberParameter = " + stringOrNumberParameter + ", stringParameter = " + stringParameter);
        else
            alert("Variant #1: stringParameter = " + stringOrNumberParameter);
    }
}

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