main repo

node_modules/es-abstract/2017/IsPromise.js

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+'use strict';
+
+var callBound = require('call-bind/callBound');
+
+var $PromiseThen = callBound('Promise.prototype.then', true);
+
+var Type = require('./Type');
+
+// https://262.ecma-international.org/6.0/#sec-ispromise
+
+module.exports = function IsPromise(x) {
+	if (Type(x) !== 'Object') {
+		return false;
+	}
+	if (!$PromiseThen) { // Promises are not supported
+		return false;
+	}
+	try {
+		$PromiseThen(x); // throws if not a promise
+	} catch (e) {
+		return false;
+	}
+	return true;
+};