es6.number.constructor.js

'use strict';
var global            = require('./_global')
  , has               = require('./_has')
  , cof               = require('./_cof')
  , inheritIfRequired = require('./_inherit-if-required')
  , toPrimitive       = require('./_to-primitive')
  , fails             = require('./_fails')
  , gOPN              = require('./_object-gopn').f
  , gOPD              = require('./_object-gopd').f
  , dP                = require('./_object-dp').f
  , $trim             = require('./_string-trim').trim
  , NUMBER            = 'Number'
  , $Number           = global[NUMBER]
  , Base              = $Number
  , proto             = $Number.prototype
  // Opera ~12 has broken Object#toString
  , BROKEN_COF        = cof(require('./_object-create')(proto)) == NUMBER
  , TRIM              = 'trim' in String.prototype;

// 7.1.3 ToNumber(argument)
var toNumber = function(argument){
  var it = toPrimitive(argument, false);
  if(typeof it == 'string' && it.length > 2){
    it = TRIM ? it.trim() : $trim(it, 3);
    var first = it.charCodeAt(0)
      , third, radix, maxCode;
    if(first === 43 || first === 45){
      third = it.charCodeAt(2);
      if(third === 88 || third === 120)return NaN; // Number('+0x1') should be NaN, old V8 fix
    } else if(first === 48){
      switch(it.charCodeAt(1)){
        case 66 : case 98  : radix = 2; maxCode = 49; break; // fast equal /^0b[01]+$/i
        case 79 : case 111 : radix = 8; maxCode = 55; break; // fast equal /^0o[0-7]+$/i
        default : return +it;
      }
      for(var digits = it.slice(2), i = 0, l = digits.length, code; i < l; i++){
        code = digits.charCodeAt(i);
        // parseInt parses a string to a first unavailable symbol
        // but ToNumber should return NaN if a string contains unavailable symbols
        if(code < 48 || code > maxCode)return NaN;
      } return parseInt(digits, radix);
    }
  } return +it;
};

if(!$Number(' 0o1') || !$Number('0b1') || $Number('+0x1')){
  $Number = function Number(value){
    var it = arguments.length < 1 ? 0 : value
      , that = this;
    return that instanceof $Number
      // check on 1..constructor(foo) case
      && (BROKEN_COF ? fails(function(){ proto.valueOf.call(that); }) : cof(that) != NUMBER)
        ? inheritIfRequired(new Base(toNumber(it)), that, $Number) : toNumber(it);
  };
  for(var keys = require('./_descriptors') ? gOPN(Base) : (
    // ES3:
    'MAX_VALUE,MIN_VALUE,NaN,NEGATIVE_INFINITY,POSITIVE_INFINITY,' +
    // ES6 (in case, if modules with ES6 Number statics required before):
    'EPSILON,isFinite,isInteger,isNaN,isSafeInteger,MAX_SAFE_INTEGER,' +
    'MIN_SAFE_INTEGER,parseFloat,parseInt,isInteger'
  ).split(','), j = 0, key; keys.length > j; j++){
    if(has(Base, key = keys[j]) && !has($Number, key)){
      dP($Number, key, gOPD(Base, key));
    }
  }
  $Number.prototype = proto;
  proto.constructor = $Number;
  require('./_redefine')(global, NUMBER, $Number);
}