You can do this in multiple ways. I have listed some ways you can validate your date.

Solution 1

function isValidDate(inputDate) {
    return !isNaN(Date.parse(inputDate);
}

Solution 2

function isValidDate(inputDate) {
    const date_regex = /^(0[1-9]|1\d|2\d|3[01])-(0[1-9]|1[0-2])-(19|20)\d{2}$/;
    return date_regex.test(inputDate)
}

function getDay(date) {
  const days = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];
  if (isValidDate(date)) {
    const myDate = new Date(date);
    
    return days[myDate.getDay()];
  }
  
  return "Invalid Date"
}

console.log(getDay('12-01-1994'));

console.log(getDay('12-01-0001'));

In your case

function isValidDate(inputDate) {
    return !isNaN(Date.parse(inputDate);
}
class Inputdate extends React.Component {
       state={
           inputDate:''
       }
    
     
   render() {
          console.log(this.state)
        return (
          <div>
            <input
                name="date"
              type="text"
              value={this.state.value}
              placeholder="dd-mm-yyyy"
              onChange={(e)=> {
                 if(isValidDate(e.target.value)){
                    this.setState({inputDate : e.target.value.replace('-', '/')})
                 }
              }}
            />
            <p>{this.state.inputDate}</p>
          </div>
        );
      }
    }