How to get a variable type in Typescript?

I have a variable.

abc:number|string;

How can I check its type? I want to do something like below:

if (abc.type === "number") {
    // do something
}

For :

abc:number|string;

Use the JavaScript operator typeof:

if (typeof abc === "number") {
    // do something
}

TypeScript understands typeof 🌹

This is called a typeguard.
More

For classes you would use instanceof e.g.

class Foo {}
class Bar {} 

// Later
if (fooOrBar instanceof Foo){
  // TypeScript now knows that `fooOrBar` is `Foo`
}

There are also other type guards e.g. in etc https://basarat.gitbook.io/typescript/type-system/typeguard

Stack Overflow Q#35546421, score: 467