any vs unknown

Both are top types in type hierarchy.

… we’re allowed to do everything with any

… we’re not allowed to do anything with unknown

Example 1

function foo(bar: any): string {
    return bar; // Okay - any is assignable to anything
}

function foo(bar: unknown): string {
    return bar; // NOT okay!
}

Example 2

let vAny: any = 10;          // We can assign anything to any
let vUnknown: unknown =  10; // We can assign anything to unknown just like any 


let s1: string = vAny;     // Any is assignable to anything 
let s2: string = vUnknown; // Invalid; we can't assign vUnknown to any other type (without an explicit assertion)

vAny.method();     // Ok; anything goes with any
vUnknown.method(); // Not ok; we don't know anything about this variable

References

• Lesson 10: TypeScript in 50 Lessions
• https://stackoverflow.com/questions/51439843/unknown-vs-any