jQuery OnChange根本不起作用

Question

I am trying to trigger an onchange on a select box, to show the value that has been selected as an alert.

My current select box code is as follows:

<span class="location select-box">
  <input class="value-holder" type="text" disabled="disabled" placeholder="Select a Location">
<div class="advanced-select-button">
  <i class="fa fa-chevron-down"></i>
</div>
<ul class="select-clone custom-list">
  <li data-value="1">Advertising</li>
  <li data-value="2">Airport</li>
  <li data-value="3">Cars</li>
  <li data-value="4">Education</li>
  <li data-value="5">Entertainment</li>
  <li data-value="6">Garden</li>
  <li data-value="2">Airport</li>
  <li data-value="3">Cars</li>
  <li data-value="4">Education</li>
  <li data-value="5">Entertainment</li>
  <li data-value="6">Garden</li>
  <li data-value="2">Airport</li>
  <li data-value="3">Cars</li>
</ul>

<select name="Select_Location" data-placeholder="Select a Location">
   <option>Select Category</option>
          <option value="1">Advertising</option>
          <option value="2">Airport</option>
          <option value="3">Cars</option>
          <option value="4">Education</option>
          <option value="5">Entertainment</option>
          <option value="6">Garden</option>
          <option value="2">Airport</option>
          <option value="3">Cars</option>
          <option value="4">Education</option>
          <option value="5">Entertainment</option>
          <option value="6">Garden</option>
          <option value="2">Airport</option>
          <option value="3">Cars</option>
        </select>
      </span>

My current jquery script is as follows:

<script>
    $('select').on('change', function() {
    alert( this.value );
    })
</script>

I can't see where I am going wrong, or what I am doing wrong here. The above Jquery code is just one of many iterations I've tried without success.

If someone can figure this out for me - I would be eternally grateful.

Thanks in advance.

ps - if you would like to see an example - I can provide a URL.

Answer 1

You need to wrap your code in document-ready handler.

A page can't be manipulated safely until the document is "ready." jQuery detects this state of readiness for you. Code included inside $( document ).ready() will only run once the page Document Object Model (DOM) is ready for JavaScript code to execute.

Example

$(document).ready(function() {
    //Your code
});

 $(document).ready(function() { //Your code $('select').on('change', function() { alert(this.value); }) }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select name="Select_Location" data-placeholder="Select a Location"> <option>Select Category</option> <option value="1">Advertising</option> <option value="2">Airport</option> <option value="3">Cars</option> <option value="4">Education</option> <option value="5">Entertainment</option> <option value="6">Garden</option> <option value="2">Airport</option> <option value="3">Cars</option> <option value="4">Education</option> <option value="5">Entertainment</option> <option value="6">Garden</option> <option value="2">Airport</option> <option value="3">Cars</option> </select> 

Answer 2

Use like

   $(function() {
      $('select').on('change', function() {
        alert( this.value );
        })
    });

Answer 3

 $(document).ready(function(){ $('select').on('change', function() { alert( this.value ); }) }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <span class="location select-box"> <input class="value-holder" type="text" disabled="disabled" placeholder="Select a Location"> <div class="advanced-select-button"> <i class="fa fa-chevron-down"></i> </div> <ul class="select-clone custom-list"> <li data-value="1">Advertising</li> <li data-value="2">Airport</li> <li data-value="3">Cars</li> <li data-value="4">Education</li> <li data-value="5">Entertainment</li> <li data-value="6">Garden</li> <li data-value="2">Airport</li> <li data-value="3">Cars</li> <li data-value="4">Education</li> <li data-value="5">Entertainment</li> <li data-value="6">Garden</li> <li data-value="2">Airport</li> <li data-value="3">Cars</li> </ul> <select name="Select_Location" data-placeholder="Select a Location"> <option>Select Category</option> <option value="1">Advertising</option> <option value="2">Airport</option> <option value="3">Cars</option> <option value="4">Education</option> <option value="5">Entertainment</option> <option value="6">Garden</option> <option value="2">Airport</option> <option value="3">Cars</option> <option value="4">Education</option> <option value="5">Entertainment</option> <option value="6">Garden</option> <option value="2">Airport</option> <option value="3">Cars</option> </select> </span>