index.js
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'use strict';
var toStr = Object.prototype.toString;
var fnToStr = Function.prototype.toString;
var isFnRegex = /^\s*(?:function)?\*/;
var hasToStringTag = require('has-tostringtag/shams')();
var getProto = Object.getPrototypeOf;
var getGeneratorFunc = function () { // eslint-disable-line consistent-return
if (!hasToStringTag) {
return false;
}
try {
return Function('return function*() {}')();
} catch (e) {
}
};
var GeneratorFunction;
module.exports = function isGeneratorFunction(fn) {
if (typeof fn !== 'function') {
return false;
}
if (isFnRegex.test(fnToStr.call(fn))) {
return true;
}
if (!hasToStringTag) {
var str = toStr.call(fn);
return str === '[object GeneratorFunction]';
}
if (!getProto) {
return false;
}
if (typeof GeneratorFunction === 'undefined') {
var generatorFunc = getGeneratorFunc();
GeneratorFunction = generatorFunc ? getProto(generatorFunc) : false;
}
return getProto(fn) === GeneratorFunction;
};