Simple TypeScript implementation of mixins.

mixin.ts

// Base class for any object using mixins.
class Base {
    // Member function to include a mixin in this class.
    include(target, mixin, includeProperties?: bool) {
        for (var name in mixin) {
            if (!target.hasOwnProperty(name)) {
                if (typeof mixin[name] === "function" || includeProperties) {
                    target[name] = mixin[name];
                }
            }
        }
    }
}

// An interface to describe the contract of the mixin.
interface ILogger {
    Log: (text: string) => void;
}

// A class that is our mixin.
class Logger implements ILogger {
    Log = (text: string) => {
        console.log(text);
    }
}

// A class that includes our mixin.
class MyClass extends Base implements ILogger {
    constructor() {
        super();
            
        // Call this method from super to pull everything in.
        this.include(this, new Logger());
    }

    // Dummy declaration. I know. But it does work.
    Log: (text:string) => void;
}