48 lines
1.2 KiB
JavaScript
48 lines
1.2 KiB
JavaScript
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'use strict';
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var callBound = require('call-bound');
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var safeRegexTest = require('safe-regex-test');
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var toStr = callBound('Object.prototype.toString');
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var fnToStr = callBound('Function.prototype.toString');
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var isFnRegex = safeRegexTest(/^\s*async(?:\s+function(?:\s+|\()|\s*\()/);
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var hasToStringTag = require('has-tostringtag/shams')();
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var getProto = require('get-proto');
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var getAsyncFunc = function () { // eslint-disable-line consistent-return
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if (!hasToStringTag) {
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return false;
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}
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try {
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return Function('return async function () {}')();
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} catch (e) {
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}
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};
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/** @type {import('.').AsyncFunction | false} */
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var AsyncFunction;
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/** @type {import('.')} */
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module.exports = function isAsyncFunction(fn) {
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if (typeof fn !== 'function') {
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return false;
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}
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if (isFnRegex(fnToStr(fn))) {
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return true;
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}
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if (!hasToStringTag) {
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var str = toStr(fn);
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return str === '[object AsyncFunction]';
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}
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if (!getProto) {
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return false;
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}
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if (typeof AsyncFunction === 'undefined') {
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var asyncFunc = getAsyncFunc();
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// eslint-disable-next-line no-extra-parens
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AsyncFunction = asyncFunc ? /** @type {import('.').AsyncFunction} */ (getProto(asyncFunc)) : false;
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}
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return getProto(fn) === AsyncFunction;
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};
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