git.r.bdr.sh - rbdr/dotfiles/blob

   1 // Based on: https://github.com/mathiasbynens/String.prototype.codePointAt
   2 // Thanks @mathiasbynens !
   3
   4 'use strict';
   5
   6 var toInteger  = require('../../../number/to-integer')
   7   , validValue = require('../../../object/valid-value');
   8
   9 module.exports = function (pos) {
  10         var str = String(validValue(this)), l = str.length, first, second;
  11         pos = toInteger(pos);
  12
  13         // Account for out-of-bounds indices:
  14         if (pos < 0 || pos >= l) return undefined;
  15
  16         // Get the first code unit
  17         first = str.charCodeAt(pos);
  18         if ((first >= 0xD800) && (first <= 0xDBFF) && (l > pos + 1)) {
  19                 second = str.charCodeAt(pos + 1);
  20                 if (second >= 0xDC00 && second <= 0xDFFF) {
  21                         // http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
  22                         return (first - 0xD800) * 0x400 + second - 0xDC00 + 0x10000;
  23                 }
  24         }
  25         return first;
  26 };