在jQuery中，我的功能无法正常工作

Question

I trying to make two conditional statement with jQuery like this.

$('#user_name, #user_email, #user_password').keyup(function () {
    if ($('#output-name').is('.field-output-comple') &&
            $('#output-email').is('.field-output-comple') &&
            $('#output-password').is('.field-output-comple') &&
            $('#confirm-terms-of-use').is(':checked')
    ) {
        $('#register-button').removeAttr('disabled');
    } else {
        $('#register-button').attr('disabled', 'disabled');
    }
});

$('#confirm-terms-of-use').change(function() {
    if ($('#output-name').is('.field-output-comple') &&
            $('#output-email').is('.field-output-comple') &&
            $('#output-password').is('.field-output-comple') &&
            $('#confirm-terms-of-use').is(':checked')
    ) {
        $('#register-button').removeAttr('disabled');
    } else {
        $('#register-button').attr('disabled', 'disabled');
    }
});

But you know this code is duplicated.

if ($('#output-name').is('.field-output-comple') &&
    $('#output-email').is('.field-output-comple') &&
    $('#output-password').is('.field-output-comple') &&
    $('#confirm-terms-of-use').is(':checked')
) { 
    $('#register-button').removeAttr('disabled');
} else {
    $('#register-button').attr('disabled', 'disabled');
}

So I make this code with function like this.

$('#user_name, #user_email, #user_password').keyup(isValidPassword())
$('#confirm-terms-of-use').change(isValidPassword())

function isValidPassword() {
    if ($('#output-name').is('.field-output-comple') &&
            $('#output-email').is('.field-output-comple') &&
            $('#output-password').is('.field-output-comple') &&
            $('#confirm-terms-of-use').is(':checked')
    ) {
        $('#register-button').removeAttr('disabled');
    } else {
        $('#register-button').attr('disabled', 'disabled');
    }
}

But it does not worked well. No error but isValidPassword dose not output anything maybe. Where did I make mistake? Thank you for reading.

Answer 1

You need to pass the function reference to the event handlers, you are calling the function isValidPassword and is passing the value returned by it undefined as the event handler.

$('#user_name, #user_email, #user_password').keyup(isValidPassword)
$('#confirm-terms-of-use').change(isValidPassword)

Answer 2

This isn't doing what you think:

.keyup(isValidPassword())

This doesn't pass the isValidPassword function itself to keyup , it executes the function and passes the result of that function. And that function doesn't return anything, so its result is undefined .

Don't execute the function, just pass the function itself as a variable:

.keyup(isValidPassword)