VueJS method to decode Base64 encoded strings

vue-decodebase64.vue

methods: {
  decodeBase64: function (string) {
    var characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='
    var result = ''
    var i = 0
    do {
      var b1 = characters.indexOf(string.charAt(i++))
      var b2 = characters.indexOf(string.charAt(i++))
      var b3 = characters.indexOf(string.charAt(i++))
      var b4 = characters.indexOf(string.charAt(i++))
      var a = ((b1 & 0x3F) << 2) | ((b2 >> 4) & 0x3)
      var b = ((b2 & 0xF) << 4) | ((b3 >> 2) & 0xF)
      var c = ((b3 & 0x3) << 6) | (b4 & 0x3F)
      result += String.fromCharCode(a) + (b ? String.fromCharCode(b) : '') + (c ? String.fromCharCode(c) : '')
    } while (i < string.length)
    return result
  }
}