How to copy values dynamically from one object to 'this' without modifying the destination in Typescript?

After searching everywhere, I didn't find a working answer.

How to map values dynamically from one object to 'this' without modifying the target in Typescript?

const bigTodo = {
  name: "aaaaaaa",
  unwantedProperty: "Nooooooo"
}

.....

export class SmallTodo {
    name: string;

    constructor(bigTodo: any){
        _.assign(this,bigTodo)       // NOT working
        _.assignIn(this,bigTodo)     // NOT working
        _.merge(this,bigTodo)        // NOT working
        _.extend(this,bigTodo)       // NOT working
        Object.assign(this, fields); // NOT working

        for (const prop in bigTodo.keys()) { 
          if (this.hasOwnProperty(prop)) {
            this[prop] = bigTodo[prop]; // NOT working not compatible with type 'any'
          }
        }
    }
}

Expected result:

SmallTodo = {
    name: "aaaaaaa"
}

UNWANTED result:

SmallTodo = {
    name: "aaaaaaa",
    unwantedProperty: "Nooooooo"
}

When you initialise property with some value you can call getOwnProperty on this. Something like below

const bigTodo = {
  name: "aaaaaaa",
  unwantedProperty: "Nooooooo"
}

class SmallTodo {
  name: string = "";

  constructor(bigTodo: any) {    
    for (const prop in bigTodo) {
      if (this.hasOwnProperty(prop)) {
        this[prop as keyof typeof this] = bigTodo[prop];
      }
    }
  }
}


console.log(new SmallTodo(bigTodo));
console.log(bigTodo);