Any vs Unknown

Intro to Any Vs Unknown
Intro to Any Vs Unknown
TypeScript has two types for "I don't know what this is": any and unknown. They behave very differently.

The any Type

any disables type checking entirely. You can do anything with any:
let value: any = 'hello'
value.foo.bar.baz() // No error! (but will crash at runtime)
value = 42
value.toUpperCase() // No error! (but will crash at runtime)
any is an escape hatch that removes type safety. Use it sparingly, if at all.

The unknown Type

unknown is the type-safe version. You must narrow it before use:
let value: unknown = 'hello'
value.toUpperCase() // ❌ Error: Object is of type 'unknown'

if (typeof value === 'string') {
	value.toUpperCase() // ✅ Now TypeScript knows it's a string
}

When to Use Each

ScenarioUse
External dataunknown
Migrating JS to TSany
Third-party libraryany
JSON.parse resultunknown
User inputunknown
Prefer unknown over any. It forces you to verify the type before using the value, catching potential bugs.
In this exercise, you'll compare any and unknown and practice refactoring escape hatches into safer checks.
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