0;
        return {
          next(v) {
            count++;
            return { value: count, done: false };
          },
        };
      },
    };
    
    function* gf() {
      yield* iterable;
      return "gf return value";
    }
    
    const gen = gf();
    gen.next(); // First next() starts the yield* expression
    gen.throw(20); // TypeError: The iterator does not provide a 'throw' method.
    

##  Specifications

Specification  
---  
[ ECMAScript Language Specification  
#  sec-generator-function-definitions-runtime-semantics-evaluation
](https://tc39.es/ecma262/multipage/ecmascript-language-functions-and-
classes.html#sec-generator-function-definitions-runtime-semantics-evaluation)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ Iteration protocols ](/en-US/docs/Web/JavaScript/Reference/Iteration_protocols)
  * [ ` function* ` ](/en-US/docs/Web/JavaScript/Reference/Statements/function*)
  * [ ` function* ` expression ](/en-US/docs/Web/JavaScript/Reference/Operators/function*)
  * [ ` yield ` ](/en-US/docs/Web/JavaScript/Reference/Operators/yield)

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