replace character at certain position inside javascript

Question

if I have string inside javascript function like

function someFunction(){
   var myStr = "12345678911";
   var maskedStr = "";       
}

how can I use myStr values with * to maskedStr contain string like

var maskedStr = "1234567*91*"; 

Answer 1

function someFunction(){
   var myStr = "12345678911";
   var maskedStr = myStr.replace("9", "*");       
}