Convert excel column alphabet (e.g. AA) to number (e.g., 25)

Question

In my grid the column headers are named A,B,C...,AA,AB,AC,...etc like an excel spreadsheet. How can I convert the string to number like: A => 1, B =>

Answer 1

// Given Column to Number
function colToNumber(str) {
  var num = 0
  var i = 0
  while (i < str.length ) {
    num = str[i].charCodeAt() - 64 + num * 26;
    i++; 
  }
  return num;
}

//Given Number to Column name
function numberToCol(num) {
  var str = '', q, r;    
  while (num > 0) {
    q = (num-1) / 26;
    r = (num-1) % 26
    num = Math.floor(a) 
    str = String.fromCharCode(65 + r) + str;
  }
  return str;
}