判断一个函数是普通函数还是生成器函数
fn1 = function *(){}
fn1.constructor.name
//"GeneratorFunction"
fn1 = function (){}
fn1.constructor.name
// "Function"
fn1.name
// "fn1"
koa-convert里有判断实现
'use strict';
var toStr = Object.prototype.toString;
var fnToStr = Function.prototype.toString;
var isFnRegex = /^\s*(?:function)?\*/;
var hasToStringTag = typeof Symbol === 'function' && typeof Symbol.toStringTag === 'symbol';
var getProto = Object.getPrototypeOf;
var getGeneratorFunc = function () { // eslint-disable-line consistent-return
if (!hasToStringTag) {
return false;
}
try {
return Function('return function*() {}')();
} catch (e) {
}
};
var generatorFunc = getGeneratorFunc();
var GeneratorFunction = generatorFunc ? getProto(generatorFunc) : {};
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]';
}
return getProto(fn) === GeneratorFunction;
};