SOURCE

var card='123845785238542307';
var strcard=card.replace(/^(.{4})(?:\d+)(.{4})$/,"$1******$2");
console.log(strcard)

let now_money = "9947.52"

let m = parseInt(now_money)
console.log(m);
let str = m.toString()
let s = str.substr(1,1)
let e = str.substr(str.length-1,1)
console.log(s+'**'+e)