Question

所以我有这个代码，我说if website_name===""显示错误，但它似乎不起作用，因为如果我输入内容并将其删除以便它为空它仍会显示它＆＃39 ; s有效所以它运行else语句，但是如果我键入一个数字然后我得到一个错误，但我需要它也适用于空值。

var message;
    var inputField = document.getElementById("website_name");
$( "#website_name" ).keyup(function() {
  if(website_name==="" || !/^[a-z]*$/.test(this.value))
  {
    $("#website_name").css('border', '3px solid red');
    inputField.style.backgroundColor = "#f27676";
    message = 'Only lower case characters allowed!';
    $('div.modal-body .msgPlaceholder').empty().append(message);
  }else{
    $("#website_name").css('border', '3px solid green');
    inputField.style.backgroundColor = "#56c145";
    message = 'Your name is correct';
    $('div.modal-body .msgPlaceholder').empty().append(message);
  }
});

Answer 1

您必须使用this.value == ""而不是website_name == ""，因为website_name不是variable

如果您想在检查之前使用toLowerCase，请尝试以下操作：

var val = this.value.toLowerCase();
if (val == "")

var message;
var inputField = document.getElementById("website_name");
$("#website_name").keyup(function() {
  if (this.value == "" || !/^[a-z]*$/.test(this.value)) {
    $("#website_name").css('border', '3px solid red');
    inputField.style.backgroundColor = "#f27676";
    message = 'Only lower case characters allowed!';
    $('div.modal-body .msgPlaceholder').empty().append(message);
  } else {
    $("#website_name").css('border', '3px solid green');
    inputField.style.backgroundColor = "#56c145";
    message = 'Your name is correct';
    $('div.modal-body .msgPlaceholder').empty().append(message);
  }
});

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

如果值为空，则验证不起作用

1 个答案: