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musix-oss/node_modules/es-abstract/2017/IsPromise.js
2020-03-03 22:30:50 +02:00

25 lines
490 B
JavaScript

'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;
};