parseInt
let str = "30"
let toInt = parseInt(str)
parseFloat
let str = "10"
let toFloat = parseFloat(str)
Number
let str = "15"
let a = Number(str)
let x = 123;
let a = String(x)
let a = x.toString();
let a = x.toString(2); // 문자형 1111011(2진법)
let a = x.toString(16); //문자형 7b(16진법)
let a = x.toFixed();
let a = x.toFixed(1); //문자형 123.0
https://velog.io/@yunsungyang-omc/JS-자바스크립트의-형변환Type-Casting