Most client-side validation nowadays is usually made through onsubmit validations. Although it is pretty convenient, it may be quite annoying for a user to find only at the end that most of their inputs are invalid and must enter them once again. If onblur validations is not enough, keyperss validation is the next step.

Here is another alternative to the usual onsubmit validations for forms. Instead of validating a form only at the end, why not validate it as the user is typing their input. This is where keypress validations come in. We can capture it through the onkeypress event.

Here are some examples of keypress validations:

Only integers are allowed:
Only alphanumeric characters are allowed:
No spaces are allowed:

Here is an example keypress validation function: Read more »