JavaScript Generator

# JavaScript Generator (function*)

The function* declaration (function keyword followed by an asterisk) defines a generator function, which returns a Generator object.

#### First Seen
```javascript
function* work() {
  // server return array dataUsers
  const newUsers = [...users].concat([{ name: "Any", age: 39 }]);
  yield put(actionSuccess({ users: newUsers }));
}

function* watch() {
  yield takeLatest(someAction.type, work);
}

export default function* rootSaga() {
  yield all([watch()]);
}
```
from [React Redux Example](https://codesandbox.io/s/redux-toolkit-state-new-array-forked-fgeym?file=/src/redux/sagas/sagas.js)

#### JavaScript Demo: Statement - Function*
```javascript
function* generator(i) {
  yield i;
  yield i + 10;
}

const gen = generator(10);

console.log(gen.next().value);
// Expected output: 10

console.log(gen.next().value);
// Expected output: 20
```

#### Syntax
```javascript
function* name(param0) {
  statements
}
function* name(param0, param1) {
  statements
}
function* name(param0, param1, /* … ,*/ paramN) {
  statements
}
```

#### Source

**Reference:** [Mozilla JavaScript function*](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function*)

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