The add comment section in the Comments component will allow the signed-in user to type in the comment text:
It will contain an avatar with the user's photo and a text field, which will add the comment when the user presses the Enter key.
mern-social/client/post/Comments.js:
<CardHeader avatar={<Avatar className={classes.smallAvatar} src={'/api/users/photo/'+auth.isAuthenticated().user._id}/>} title={<TextField onKeyDown={this.addComment} multiline value={this.state.text} onChange={this.handleChange('text')} placeholder="Write something ..." className={classes.commentField} margin="normal"/>} className={classes.cardHeader} ...
