How to add multiple classes in Material UI using the classes props

Using the css-in-js method to add classes to a react component, how do I add multiple components?

Here is the classes variable:

const styles = theme => ({
 container: {
  display: 'flex',
  flexWrap: 'wrap'
},
 spacious: {
  padding: 10
},
});

Here is how I used it:

    return (
     <div className={ this.props.classes.container }>

The above works, but is there a way to add both classes, without using the classNames npm package? Something like:

     <div className={ this.props.classes.container + this.props.classes.spacious}>

Answer

you can use string interpolation:

<div className={`${this.props.classes.container} ${this.props.classes.spacious}`}>