Salesforce JavaScript Developer Practice Exam

What is the output of the generator function below after two calls? function* generator(i) { yield i; yield i * 2; } const gen = generator(10); console.log(gen.next().value); console.log(gen.next().value);

1. [0, 10], [10, 20]

2. 20, 20

3. 10, 20

4. 0, 10 and 10, 20

The correct answer is: 10, 20

The output of the generator function can be explained by looking closely at how generator functions work in JavaScript. The generator function defined here takes an initial value `i`. The `yield` keyword is used to pause the function and return a value, allowing the execution to be resumed later. When the generator function `generator(10)` is called, it initializes a generator object `gen` that starts with `i` set to 10. The first call to `gen.next()` executes the generator up to the first `yield` statement, which yields the value of `i`, so the first call outputs `10`. In the second call to `gen.next()`, the execution resumes right after the first `yield` statement and continues to the next `yield`, which is `i * 2`. Since `i` is still 10, this second `yield` evaluates to `20`, so the second call outputs `20`. Therefore, after two calls to the generator, the output is indeed `10` after the first call and `20` after the second call, leading to the conclusion that the correct answer is that the output is `10` and `20`.