SOURCE

var str="adfdsfafdfajasfdkjasklfjlkjaskldf";
var i = 0, j = 0, length = 0;
var arr = [];
const ZNReg=/^[\u0391-\uFFE5]+$/;
const UpReg=/^[A-Z]+$/;     
if(str.length<=10) return;
while(length<12) {
  let temp = str.charAt(i);
  arr.push(temp);
  if(ZNReg.test(temp)) length += 2;
  else if(UpReg.test(temp)) length += 1.5;
  else length += 1;
  i++;
}
console.log(arr.join(''));