source: frontend/node_modules/is-async-function/index.js

'use strict';

var callBound = require('call-bound');
var safeRegexTest = require('safe-regex-test');

var toStr = callBound('Object.prototype.toString');
var fnToStr = callBound('Function.prototype.toString');
var isFnRegex = safeRegexTest(/^\s*async(?:\s+function(?:\s+|\()|\s*\()/);

var hasToStringTag = require('has-tostringtag/shams')();
var getProto = require('get-proto');

var getAsyncFunc = require('async-function');

/** @type {import('.')} */
module.exports = function isAsyncFunction(fn) {
        if (typeof fn !== 'function') {
                return false;
        }
        if (isFnRegex(fnToStr(fn))) {
                return true;
        }
        if (!hasToStringTag) {
                var str = toStr(fn);
                return str === '[object AsyncFunction]';
        }
        if (!getProto) {
                return false;
        }
        var asyncFunc = getAsyncFunc();
        return asyncFunc && asyncFunc.prototype === getProto(fn);
};