kitchensink/examples/node_modules/is-generator-function/index.js

Dispatch's awesome components and style guide

'use strict';

var toStr = Object.prototype.toString;
var fnToStr = Function.prototype.toString;
var isFnRegex = /^\s*function\*/;

module.exports = function isGeneratorFunction(fn) {
	if (typeof fn !== 'function') { return false; }
	var fnStr = toStr.call(fn);
	return (fnStr === '[object Function]' || fnStr === '[object GeneratorFunction]') && isFnRegex.test(fnToStr.call(fn));
};