How to make a required input field in JavaScript?

Answer 1

Check this:
https://www.w3schools.com/jsref/prop_text_required.asp

Answer 2

https://www.w3schools.com/js/js_validation.asp
https://itnext.io/https-medium-com-joshstudley-form-field-validation-with-html-and-a-little-javascript-1bda6a4a4c8c

Answer 3

You can use prompt again and again until the desired input is acquired.