Bug in toExponential() about double.js HOT 7 CLOSED

const D = require('double.js');
const inner_radius = new D('1.0')
console.log(inner_radius.toNumber())
const outer_radius = new D('2.0')
console.log(outer_radius.toNumber())
const radius = outer_radius.add(inner_radius)
console.log(radius.toNumber())
console.log(D)
console.log(outer_radius)
console.log(inner_radius)
console.log(radius)
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function Double()
Double {hi: 2, lo: 0}
Double {hi: 1, lo: 0}

$ cat a.js
import * as Double from 'double.js/dist/double.js'
const D = Double.default.Double

console.log(D)

const inner_radius = new D('1.0')
console.log(inner_radius.toNumber())
const outer_radius = new D('2.0')
console.log(outer_radius.toNumber())
const radius = outer_radius.add(inner_radius)
console.log(radius.toNumber())
console.log(outer_radius)
console.log(inner_radius)
console.log(radius)
$ node --experimental-modules a.mjs 
[Function: Double]
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Double { hi: 2, lo: 0 }
Double { hi: 1, lo: 0 }
Double { hi: 3, lo: 0 }

$ cat a.mjs
import * as Double from 'double.js/dist/double.js'
//import { Double } from 'double.js/dist/double.esm.js'
//require = require("esm")(module)
//const D = require('double.js').Double
const D = Double.default.Double

function toExponential(self, precision) {
  if (precision === undefined)
    precision = 33;
  let result = (self.hi < 0.) ? '-' : '';
  if (isNaN(self.hi))
    return 'NaN';
  if (!isFinite(self.hi))
    return result + 'Infinity';
  if (self.toNumber() == 0.)
    return '0e+0';
  let exp = self.hi.toExponential().split('e')[1];
  let str, nextDigs, shift, isPositive;
  for (let i = 0; i < precision; i += 15) {
    str = self.hi.toExponential().split('e');
    console.log('i: ', i, 'str:', str);
    isPositive = (str[0][0] != '-');
    nextDigs = str[0].replace(/^0\.|\./, '').slice(0, 15);
    console.log('nextDigs: ', nextDigs);
    if (!isPositive)
      nextDigs = nextDigs.slice(1);
    console.log('nextDigs: ', nextDigs);
    shift = D.pow2n(new D(10), parseInt(str[1]) - 14);
    console.log('shift: ', shift);
    D.sub22(self, D.mul21(shift, parseInt(nextDigs) * ((isPositive) ? 1 : -1)));
    console.log('shift: ', shift, 'self: ', self);
    nextDigs = nextDigs.slice(0, precision - i);
    console.log('nextDigs: ', nextDigs);
    result += (i != 0) ? nextDigs : nextDigs.slice(0, 1) + '.' + nextDigs.slice(1);
    console.log('result: ', result);
  }
  return result + 'e' + exp;
}

console.log(D)

const inner_radius = new D('1.0')
console.log(inner_radius.toNumber())
const outer_radius = new D('2.0')
console.log(outer_radius.toNumber())
const radius = outer_radius.add(inner_radius)
console.log(radius.toNumber())
console.log(outer_radius)
console.log(inner_radius)
console.log(radius)
console.log(toExponential(radius))
console.log(radius)

$ node --experimental-modules a.mjs 
[Function: Double]
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Double { hi: 2, lo: 0 }
Double { hi: 1, lo: 0 }
Double { hi: 3, lo: 0 }
i:  0 str: [ '3', '+0' ]
nextDigs:  3
nextDigs:  3
shift:  Double { hi: 1e-14, lo: 1.1806906454401013e-32 }
shift:  Double { hi: 3e-14, lo: 1.6131425298052268e-30 } self:  Double { hi: 2.99999999999997, lo: 1.980662698042579e-16 }
nextDigs:  3
result:  3.
i:  15 str: [ '2.99999999999997', '+0' ]
nextDigs:  299999999999997
nextDigs:  299999999999997
shift:  Double { hi: 1e-14, lo: 1.1806906454401013e-32 }
shift:  Double { hi: 2.99999999999997, lo: 1.980662698042579e-16 } self:  Double { hi: 0, lo: 0 }
nextDigs:  299999999999997
result:  3.299999999999997
i:  30 str: [ '0', '+0' ]
nextDigs:  0
nextDigs:  0
shift:  Double { hi: 1e-14, lo: 1.1806906454401013e-32 }
shift:  Double { hi: 0, lo: 0 } self:  Double { hi: 0, lo: 0 }
nextDigs:  0
result:  3.2999999999999970
3.2999999999999970e+0
Double { hi: 0, lo: 0 }