Dynamic (any) Types

Dynamic (any) Types

The any type lets a variable hold any type of value, effectively opting out of type checking.

Using any

let age: any = 25;
age = "hello";   // ✅ No error
age = true;      // ✅ No error
age = { name: "Mario" };  // ✅

any with Arrays

let mixed: any[] = [];
mixed.push(5);
mixed.push("hello");
mixed.push(true);  // All OK

any with Objects

let ninja: { name: any; age: any };
ninja = { name: "Mario", age: 25 };
ninja = { name: 123, age: "hello" };  // Both OK

Why Avoid any?

any defeats the purpose of TypeScript:

• ❌ No type checking — errors won't be caught
• ❌ No auto-completion in your IDE
• ❌ No refactoring support
• ❌ Your code becomes as error-prone as JavaScript

When any Is Acceptable

• Migrating a JavaScript project gradually
• Working with third-party libraries without type definitions
• Prototyping quickly (but refactor later)

Key Takeaways

• any allows any type — removes all type safety
• Avoid any whenever possible
• Use it only during migration or with untyped libraries
• Prefer unknown over any for safer dynamic types