throwGenerator.js

function* makeFibonacciSequenceGenerator(endIndex = Infinity) {
    let previousNumber = 0;
    let currentNumber = 1;
    let skipCount = 0;
    
    try {
      for (let currentIndex = 0; currentIndex < endIndex; currentIndex++) {
          if (skipCount === 0) {
              skipCount = yield currentNumber;
              skipCount = skipCount === undefined ? 0 : skipCount;
          } else if (skipCount > 0){
              skipCount--;
          }
 
          let nextNumber = currentNumber + previousNumber;
          previousNumber = currentNumber;
          currentNumber = nextNumber;
      }
    } catch(err) {
    	console.log(err.message); // will print ‘External throw’ on the fourth iteration.
    }
}
 
let fibonacciSequenceGenerator = makeFibonacciSequenceGenerator(50);

console.log(fibonacciSequenceGenerator.next(1).value);
console.log(fibonacciSequenceGenerator.next(3).value);
console.log(fibonacciSequenceGenerator.next().value);
fibonacciSequenceGenerator.throw(new Error('External throw'));
console.log(fibonacciSequenceGenerator.next(1).value); // undefined will be printed since the generator is done.