text: 'use strict';
  var $ = require('../internals/export');
  var toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
  var parseInt = require('../internals/number-parse-int');
  
  var INVALID_NUMBER_REPRESENTATION = 'Invalid number representation';
  var INVALID_RADIX = 'Invalid radix';
  var valid = /^[\da-z]+$/;
  
  // `Number.fromString` method
  // https://github.com/tc39/proposal-number-fromstring
  $({ target: 'Number', stat: true }, {
    fromString: function fromString(string, radix) {
      var sign = 1;
      var R, mathNum;
      if (typeof string != 'string') throw TypeError(INVALID_NUMBER_REPRESENTATION);
      if (!string.length) throw SyntaxError(INVALID_NUMBER_REPRESENTATION);
      if (string.charAt(0) == '-') {
        sign = -1;
        string = string.slice(1);
        if (!string.length) throw SyntaxError(INVALID_NUMBER_REPRESENTATION);
      }
      R = radix === undefined ? 10 : toIntegerOrInfinity(radix);
      if (R < 2 || R > 36) throw RangeError(INVALID_RADIX);
      if (!valid.test(string) || (mathNum = parseInt(string, R)).toString(R) !== string) {
        throw SyntaxError(INVALID_NUMBER_REPRESENTATION);
      }
      return sign * mathNum;
    }
  });
  