how can you convert the string of any base to integer in javascript code example

Example 1: how to change a string to number in javascript

let theInt = parseInt("5.90123"); //5
let theFloat = parseFloat("5.90123"); //5.90123

Example 2: converst strig in number in js

const numberInString = "20"; 
console.log(typeof(numberInString)) // typeof is string this is string in double quote " "
const numInNum = parseInt(numberInString) // now numberInStrings variable converted in an Integer due to parseInt
console.log(typeof(numInNum)) // this tell us the type of numInNum which is now a number