function reportError(node) {
            errors.add('Variable `' + node.name + '` is not used', node);
        }
Disallows unused variables defined with var, let or const.

Types: `Boolean`

Values: `true`

#### Example

```js
"disallowUnusedVariables": true
```

##### Valid

```js
var x=1;

function getX() {
    return x;
}

```

##### Invalid

```js
var x=1;

function getX() {
    return true;
}

```