core-js/modules/$.def.js

Standard library

var global     = require('./$.global')
  , core       = require('./$.core')
  , hide       = require('./$.hide')
  , $redef     = require('./$.redef')
  , PROTOTYPE  = 'prototype';
var ctx = function(fn, that){
  return function(){
    return fn.apply(that, arguments);
  };
};
var $def = function(type, name, source){
  var key, own, out, exp
    , isGlobal = type & $def.G
    , isProto  = type & $def.P
    , target   = isGlobal ? global : type & $def.S
        ? global[name] || (global[name] = {}) : (global[name] || {})[PROTOTYPE]
    , exports  = isGlobal ? core : core[name] || (core[name] = {});
  if(isGlobal)source = name;
  for(key in source){
    // contains in native
    own = !(type & $def.F) && target && key in target;
    // export native or passed
    out = (own ? target : source)[key];
    // bind timers to global for call from export context
    if(type & $def.B && own)exp = ctx(out, global);
    else exp = isProto && typeof out == 'function' ? ctx(Function.call, out) : out;
    // extend global
    if(target && !own)$redef(target, key, out);
    // export
    if(exports[key] != out)hide(exports, key, exp);
    if(isProto)(exports[PROTOTYPE] || (exports[PROTOTYPE] = {}))[key] = out;
  }
};
global.core = core;
// type bitmap
$def.F = 1;  // forced
$def.G = 2;  // global
$def.S = 4;  // static
$def.P = 8;  // proto
$def.B = 16; // bind
$def.W = 32; // wrap
module.exports = $def;