# Create a JavaScript function and trigger it in ConverseScript

Let's use the `functions` property:

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
        nameFunctionJs() {

        }
    }
}
```

The ConverseScript script uses the function:

```typescript
nameFunctionJs()
```

If the function has asynchronous values, let's return a promise:

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
        nameFunctionJs() {
            return new Promise((resolve, reject) => {
                // any code
                resolve()
            })
        }
    }
}
```

### Use ConverseScript parameters

Often, information is essential for the proper functioning of the function. For example, retrieve the user information or retrieve the user collection.

#### Using a magic variable

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
        nameFunctionJs() {
            const { user } = this.converse
            // any code
            user.setMagicVariable('foo', 'hello')
        }
    }
}
```

The script is as follows:

```typescript
start() {
    nameFunctionJs()
    > { :foo }
}
```

**Property converse**

The `converse` property is an object:

```typescript
{
    users: Map<User>,
    user: User,
    data: any,
    execution: Execution,
    level: String,
    ins: Object
}
```

#### Return of a function

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
        nameFunctionJs() {
            return 'hello'
        }
    }
}
```

The script is as follows:

```typescript
start() {
    str = nameFunctionJs()
    > { str }
}
```

#### Use an object

It is possible to use an object with several functions:

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
        myObj: {
            nameFunction() {

            }
        }
    }
}
```

In ConverseScript

```typescript
start() {
    myObj.nameFunction()
}
```

With specific parameters:

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
         myObj: {
            nameFunction() {
                const { user } = this.converse
            }
        }
    }
}
```

### Create a mock of the function

It is very useful to mock a function. Even though each function can be mocked in each unit test, it is also possible to change the behavior in a global way by associating the mock with a skill, which will be triggered during unit tests.

```javascript
import code from './main.converse'

export default {
    code,
    functions: {
         nameFunctionJs: {
            $call() {
                const { user } = this.converse
                return 'hello'
            },
            $mock() {
                const { user } = this.converse
                return 'fake'
            }
        }
    }
}
```