jquery - 提交按钮呈灰色，直到复选框被勾选为止？

Question

我想弄清楚如何在未选中复选框的情况下使提交按钮变灰？谁能引导我走向正确的方向。

html:

<div class = "form-group" id="myform">      
                <div class="checkbox">
                <label>
                    <input type="checkbox" id="checkbox"> I confirm that I am over 18 years of age
                </label>
            </div>
            <br><br>
            <div class ="row">
            <div class ="col-sm-6">
            <input type="submit" id="submit" class="btn btn-success btn-block btn-default" value="Submit">
            </div><div class ="col-sm-6">
            <input type="reset" class="btn btn-primary btn-block btn-default" value="Clear the Info">
            </div></div>
            <br><br><br><br><br><br><br><br><br>
            </div>

jQuery:

$(document).ready(function() {


$('#username').focus(); 
$('form').h5Validate({errorClass:'validationError' });

$('#submit').attr('disabled',true);
$('#checkbox').click(function(){
    $('#submit').attr('disabled',!this.checked);
});
$('#myform').submit(function(){
    return $('#checkbox').attr('checked');
});

});

Answer 1

为什么不在点击事件中这样做？

$(document).ready(function() {


    $('#submit').prop('disabled', true); // disabled by default

    $('#checkbox').click(function() {
       // change on checkbox click
       $('#submit').prop('disabled', !$('#checkbox').prop('checked'));
    });

});