All of the following if-statements will have the same error with their respective types.
class SomeClass {
}
const co: any = coroutine.create(() => {});
if (co instanceof SomeClass) {}
const fn: any = () => {};
if (fn instanceof SomeClass) {}
const bool: any = true;
if (bool instanceof SomeClass) {}
const num: any = 5;
if (num instanceof SomeClass) {}/usr/local/opt/lua/bin/lua5.3: dist/bundle.lua:716: attempt to index a thread value (local 'obj')
stack traceback:
dist/bundle.lua:716: in function '__TS__InstanceOf'
Some are a bit contrived, and casting as any was need to get TS to compile for some of them. However, a more real-life case happens when you have a type union:
class SomeClass {
constructor(public someFn: (this: void) => void) {}
}
function takesClassOrFunction(clsOrFn: SomeClass | ((this:void) => void)): void {
if (clsOrFn instanceof SomeClass) {
return clsOrFn.someFn()
} else {
return clsOrFn();
}
}
const noop = () => {};
const cls = new SomeClass(noop);
takesClassOrFunction(cls);
takesClassOrFunction(noop);
All of the following if-statements will have the same error with their respective types.
Some are a bit contrived, and casting as any was need to get TS to compile for some of them. However, a more real-life case happens when you have a type union: