graceful-instanceof/lib/index.js

The instanceof mechanism cross package/module versions.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _symbolFor = require('symbol-for');

var _symbolFor2 = _interopRequireDefault(_symbolFor);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

exports.default = function (key) {
  var s = _symbolFor2.default.for(key + ':hasInstance');
  return {
    is: function is(subject) {
      return subject && subject[s] === true;
    },
    attach: function attach(host) {
      if (Object(host) === host) {
        host[s] = true;
      }
    }
  };
};

module.exports = exports['default'];