# Generator Functions in JavaScript

Functions are the building block of every program. In JavaScript, we have a special function called **Generator Function.** What makes this function special? It’s an execution cycle. From the top level, it only executes till a certain part and stops further, on calling again it would continue from the instance and return if it finds the breakpoint again, this cycle continues until we add a hard stop. Now Let’s dive deep to look into the details of Generator functions.

```javascript
function* generatorCreator() {
  let counter = 0;

  while(true) {
    yield counter;
    counter += 1;
  }
}

const genOperator = generatorCreator();


genOperator.next();
genOperator.next();
genOperator.next();
```

Let’s break down the above code. If you’ve noticed in the initial line **function\* —** after the function there is an asterisk symbol which indicates to the JS compiler that it’s not a regular function but a Generator function. As it’s a while loop with true expression, which would execute this loop infinitely. Inside the loop **yield** keyword is used (this is the breakpoint that stops further executions).

The `const genOperator = generatorCreator();` is where the generator object instance is initiated, the function won’t be called at this stage. Once the [*genOperator.next*](http://genOperator.next)*();* is called, actual function execution takes place though it would stop at the *yield counter;* stage. Now when the second next method is called execution resumes from the below line, the counter is updated with **1** again the loop runs going back to yield and stopping the execution further. This process would continue whenever we call the next() function making the counter update.

**Generator Functions** are usually used in the library codebase or customs iterators. A package like redux-saga is one the best example where it’s been used extensively.