Question

我有以下Javascript检查字段是否为空。

function checkForm(form) {
    if(this.firstname.value == "") {
      alert("Please enter your First Name in the form");
      this.firstname.focus();
      return false;
    }
}

我如何使用jQuery重写它？

Answer 1

您可以使用Jquery验证执行此操作。

$(".form").validate({
    rules: {
        firstname: {
            required: true
        },
      },
    errorElement: 'div',
    errorPlacement: function (error, element) {
        var placement = $(element).data('error');
        if (placement) {
            $(placement).append(error);
        }
        else {
            error.insertAfter(element);
        }
    }
});

Jquery验证： https://jqueryvalidation.org/documentation/

Answer 2

类似

var $firstName = $(this).find( "[name='firstname']" );
if ( $firstName.val().length == 0 )
{
  alert("Please enter your First Name in the form");
  $firstName.focus();
  return false;
}

Answer 3

非常简单。详情在Snippet中评论

<强>段

＆＃13;

/* When any input has lost focus (ie blur)
|| and it's value is false, raise the alarm
*/
$('input').on('blur', function() {
  if (!$(this).val()) {
    alert('PUT SOMETHING IN THIS BOX');
  }
});

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>


<input>

＆＃13;

如何在jQuery中执行此Javascript？

3 个答案: