js-waku/web-chat/src/MessageInput.tsx

import React, { ChangeEvent, KeyboardEvent, useState } from 'react';
import { Button, Grid, TextField } from '@material-ui/core';

interface Props {
  messageHandler: (msg: string) => void;
  sendMessage: () => void;
}

export default function MessageInput(props: Props) {
    const [inputText, setInputText] = useState<string>('')

  const sendMessage = () => {
    props.sendMessage()
    setInputText('')
  }

  const messageHandler = (event: ChangeEvent<HTMLInputElement>) => {
    setInputText(event.target.value)
    props.messageHandler(event.target.value);
  };

  const keyPressHandler = (event: KeyboardEvent<HTMLInputElement>) => {
    if (event.key === 'Enter') {
      sendMessage()
    }
  }

    return (
      <Grid container spacing={2} direction='row' alignItems='center'>
        <Grid item xs={11}>
          <TextField variant='outlined'
                     label='Send a message'
                     value={inputText}
                     fullWidth
                     style={{ margin: 8 }}
                     margin="normal"
                     InputLabelProps={{
                       shrink: true,
                     }}
                     onChange={messageHandler}
                     onKeyPress={keyPressHandler}
          />
        </Grid>
        <Grid item xs={1}>
          <Button variant="contained" color="primary" size="large" onClick={sendMessage}>
            Send
          </Button>
        </Grid>
      </Grid>
    );
}