Javascript generator example

function* name([param[, param[, ... param]]]) {
   statements
}
        
            
        
     function* forever() {
    let index = 0;
    while (true) {
        yield index++;
    }
}

let f = forever();
console.log(f.next()); // 0
console.log(f.next()); // 1
console.log(f.next()); // 2