It is difficult to write portable ECMAScript code which accesses the global object. On the web, it is accessible as window or self or this or frames; on node.js, it is global or this; among those, only this is available in a shell like V8's d8 or JavaScriptCore's jsc...

 * ECMAScript Proposal, specs, and reference implementation for globalThis.
 * ref:
 * @return {object|Error} globalThis or Error.
var getGlobal = function() {
    // the only reliable means to get the global object is
    // `Function('return this')()`
    // However, this causes CSP violations in Chrome apps.
    if (typeof self !== "undefined") {
        return self;
    if (typeof window !== "undefined") {
        return window;
    if (typeof global !== "undefined") {
        return global;
    throw new Error("unable to locate global object");