You can call a generator step by step using next function
var sequence = fibonacci();
var value;
while ((value = sequence.next()) < 1000) {
console.log(value);
}
plus, maybe even a nicer solution would be something like:
function* fibonacci(limit){
let previous = 0;
let current = 1;
while(previous + current < limit) {
let temp = previous;
previous = current;
yield current = temp + current;
}
}
for(let value of fibonacci(1000)) {
console.log(value);
}