is-generator-function
v1.0.9 generator generator function es6 es2015 yield function function*
is-generator-function 
Is this a native generator function?
Example
var isGeneratorFunction = require('is-generator-function');
assert(!isGeneratorFunction(function () {}));
assert(!isGeneratorFunction(null));
assert(isGeneratorFunction(function* () { yield 42; return Infinity; }));
Tests
Simply clone the repo, npm install, and run npm test
