//to int
let strNumber = "42";
//the first method
let number = Number(strNumber);
//the second method
number = parseInt(strNumber);

//to Double and Float
//the first method
let strPi = "3.14";
let pi = parseFloat(strPi);

//the second method
let strExp = "2.71828";
let exp = +strExp;

//the third method
let strHalf = "0,5";
let half = +strHalf.replace(",", ".");

console.log("number =", number);
console.log("pi =", pi);
console.log("exp =", exp);
console.log("half =", half);