25 lines
490 B
JavaScript
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;
|
||
|
|
};
|