Can't make the validation work in Bootstrap 4

Question

I\'m trying to implement validation by Bootstrap and I\'ve pasted the following sample on my page:

Answer 1

Validation has changed as of the Bootstrap 4 beta release.

The valid state selectors use the was-validated class which would be added dynamically after validating the form via client-side JavaScript. For example...

    

        Input with success
        
        
Success! You've done it.
    
    

        Input with danger
        
        
That didn't work.
    
    

        Text
    

https://www.codeply.com/go/45rU7UOhFo

Update 2019 - Bootstrap 4.0.0
Form Validation Example Demo

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As explained in the docs, if you intend to use server-side validation you can simply set the is-valid or is-invalid classes on the form-controls...

    

        Input with success
        
        
Success! You've done it.