node_modules/es-abstract/2018/IsPromise.js


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

'use strict';

var callBound = require('../helpers/callBound');

var $PromiseThen = callBound('Promise.prototype.then', true);

var Type = require('./Type');

// https://www.ecma-international.org/ecma-262/6.0/#sec-ispromise

module.exports = function IsPromise(x) {
	if (Type(x) !== 'Object') {
		return false;
	}
	if (!$PromiseThen) { // Promises are not supported
		return false;
	}
	try {
		$PromiseThen(x); // throws if not a promise
	} catch (e) {
		return false;
	}
	return true;
};