issymbol/src/index.js

Test if something is a Symbol. Works with either native or polyfill Symbols.

// shamelessly copied from: https://github.com/medikoo/es6-symbol/blob/a665c611b96c72b177f70d2e5c253e2e0a2f22cc/is-symbol.js

var toString = Object.prototype.toString;

module.exports = function issymbol(x) {
    'use strict';
    return (x && ((typeof x === 'symbol')
        || (x['@@toStringTag'] === 'Symbol')
        || toString.call(x) === '[object Symbol]')) || false;
};