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