Regarding generator function send() javascript

Question

I was viewing generator functions in Mozilla Dev page.

There was an example code which is having send() function.

function* fibonacci() {
  var a = yield 1;
  yield a * 2;
}

var it = fibonacci();
console.log(it);          // "Generator {  }"
console.log(it.next());   // 1
console.log(it.send(10)); // 20
console.log(it.close());  // undefined
console.log(it.next());   // throws StopIteration (as the generator is now closed)

But, both chrome and Firefox (Latest version) are throwing error on send() function.

Any views on this? Is it not supported?

Answer 1

.send is part of the Legacy generator objects which are specific to the SpiderMonkey engine. It will be removed in some future release. They have already started removing/replacing the legacy generator objects with ES6 generators in parts of their code (Bug 1215846, Bug 1133277)

For the moment you can still use legacy generators in Firefox (current version as of this answer: 43.0.4). Just leave off the * when defining, and as long as the function body uses a yield statement the legacy generator will be used.

function fibonacci() {
  var a = yield 1;
  yield a * 2;
}

var it = fibonacci();
console.log(it);          
console.log(it.next());   
console.log(it.send(10)); 
console.log(it.close());  
console.log(it.next());