如何隱藏div直到某個字段的值大於零

Question

因此，我要在此處完成的工作是通過隱藏最后一部分直到某個字段的值大於零，從而防止人們進入表格的其余部分，直到他們專注於第一部分為止。

這是我的HTML：

<div class="fieldcontainer">
<label>E-mail:</label>
<input type="email" name="email" maxlength="100" id="email" required>
</div>
<br><br>
<div id="projectinformation" style="display:none">
<h3>Project Information</h3>
<div class="fieldcontainer">
<label>Project Name:</label>
<input type="text" name="project_name" maxlength="70" required>
</div>
<br><br>
<div class="fieldcontainer">
<label>Project Number:</label>
<input type="text" name="project_number" required>
</div>
<br><br>
<div class="fieldcontainer">
<label>Business Unit:</label>
<select name="business_unit" required>
    <option>--Select--</option>
</select>
</div>
<br><br>
<div class="fieldcontainer">
<label>Project Address:</label>
<input type="text" name="address" required>
</div>
<br><br>
<div class="fieldcontainer">
<label>Number of users on site:</label>
<select id="numberofstaff">
    <option class="staffselection" value="">--Select--</option>
    <option class="staffselection" value="smalljobsite">1-3 staff</option>
    <option class="staffselection" value="mediumjobsite">4-7 staff</option>
    <option class="staffselection" value="largejobsite">8+ staff</option>
</select>
</div>
</div>

這是我的JS：

while (document.getElementById('email').value > ""){
document.getElementById('projectinformation').style.display = 'initial';
}

Answer 1

您可能想要一個事件處理程序，並檢查輸入值的長度，然后顯示表單的其余部分

document.getElementById('email').addEventListener('input', function() {
    if ( this.value.length > 0 ) {
        document.getElementById('projectinformation').style.display = 'block';
    }
}, false);

或在jQuery中

$('#email').on('input', function() {
    if (this.value.length > 0) $('#projectinformation').show();
});

Answer 2

這是jQuery解決方案：

  $("#email").keyup(function() {
      if($(this).val().length)     
         $('#projectinformation').show();
      else 
         $('#projectinformation').hide();
  });

如果要驗證是否是有效的電子郵件然后顯示該表格，可以執行以下操作：（ https://stackoverflow.com/a/2855946/1845408 ）：

 function isValidEmailAddress(emailAddress) {
      var pattern = new RegExp(/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i);
      return pattern.test(emailAddress);
 };


  $("#email").keyup(function() {
      if(isValidEmailAddress($(this).val())) {    
             $('#projectinformation').show();
          else 
            $('#projectinformation').hide();
  });