Form validation and enabling the submit button

I have a normal ActiveForm instance (like generated with gii) with some inputs and some rules, like required or match. All validation can be done in the browser and by JS code of yii (yii.activeForm.js and yii.validation.js) without server validation.

What I simply would like to have, is, that the submit button of the form gets only enabled if all inputs are filled with valid data. Otherwise it should be disabled. How can I achieve this?

I know that I could do $('#form').yiiActiveForm('validate'), but that is doing more than I want. It shows the error messages for each input. This might be more useful on form submit. Consider that a page with the form is just opened, user enters data into the first input. So calling $('#form').yiiActiveForm('validate') on change/blur would cause that all inputs get validated and then showing all the error messages, although the user did not had a chance to enter all data. So this does not seem the right approach.

Using afterValidate neither seems to be the right approach, since it also has something to do with validating all inputs and showing all error messages.

I would need something like $('#form').yiiActiveForm('isValid') just returning bool. Then I could check this and enable/disable the submit button on change of every input.