source: imaps-frontend/node_modules/has-symbols/shams.js@ d565449

'use strict';

/* eslint complexity: [2, 18], max-statements: [2, 33] */
module.exports = function hasSymbols() {
        if (typeof Symbol !== 'function' || typeof Object.getOwnPropertySymbols !== 'function') { return false; }
        if (typeof Symbol.iterator === 'symbol') { return true; }

        var obj = {};
        var sym = Symbol('test');
        var symObj = Object(sym);
        if (typeof sym === 'string') { return false; }

        if (Object.prototype.toString.call(sym) !== '[object Symbol]') { return false; }
        if (Object.prototype.toString.call(symObj) !== '[object Symbol]') { return false; }

        // temp disabled per https://github.com/ljharb/object.assign/issues/17
        // if (sym instanceof Symbol) { return false; }
        // temp disabled per https://github.com/WebReflection/get-own-property-symbols/issues/4
        // if (!(symObj instanceof Symbol)) { return false; }

        // if (typeof Symbol.prototype.toString !== 'function') { return false; }
        // if (String(sym) !== Symbol.prototype.toString.call(sym)) { return false; }

        var symVal = 42;
        obj[sym] = symVal;
        for (sym in obj) { return false; } // eslint-disable-line no-restricted-syntax, no-unreachable-loop
        if (typeof Object.keys === 'function' && Object.keys(obj).length !== 0) { return false; }

        if (typeof Object.getOwnPropertyNames === 'function' && Object.getOwnPropertyNames(obj).length !== 0) { return false; }

        var syms = Object.getOwnPropertySymbols(obj);
        if (syms.length !== 1 || syms[0] !== sym) { return false; }

        if (!Object.prototype.propertyIsEnumerable.call(obj, sym)) { return false; }

        if (typeof Object.getOwnPropertyDescriptor === 'function') {
                var descriptor = Object.getOwnPropertyDescriptor(obj, sym);
                if (descriptor.value !== symVal || descriptor.enumerable !== true) { return false; }
        }

        return true;
};