Convert a string to it's correct datatype (number, boolean, or string)

cast.js

function isNumeric(str){
  return !isNaN(str);
}
    
function isBoolean(str){
  return (str === "true" || str === "false");
}

// 1. +val casts any number (int, float) from a string
// 2. String(val) === "true" converts a string to bool

var v = (isNumeric(val) ? +val : isBoolean(val) ? (String(val).toLowerCase() === "true") : val);