Jquery：根据下拉选择的值动态更改 img src

Question

I would like to dynamically display an image after the user has selected it. The different options are generated from a SQL query.

It works when I specify the image as a value:

<select id="SelectLogo" onchange="document.getElementById('logo').src='/images/'+this.value" >
   <option value="img1.png">Image 1</option>
   <option value="img2.png">Image 2</option>
   <option value="img3.png">Image 3</option>
</select>
<img id="logo" src="">

But now I need to post an Id but not the image name. I have tried that:

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <select id="SelectLogo" onchange="document.getElementById('logo').src='/images/'+$(this).attr('data-img')" > <option value="1" data-img="img1.png">Image 1</option> <option value="2" data-img="img2.png">Image 2</option> <option value="3" data-img="img3.png">Image 3</option> </select> <img id="logo" src="">

I got an error: undefined

Answer 1

You can use $(this).find('option:selected').data('img') to get the selected option data-attribute.

Demo Code :

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <select id="SelectLogo" onchange="document.getElementById('logo').src='/images/'+$(this).find('option:selected').data('img')" > <option value="1" data-img="img1.png">Image 1</option> <option value="2" data-img="img2.png">Image 2</option> <option value="3" data-img="img3.png">Image 3</option> </select> <img id="logo" src="">

Answer 2

Also you can use jquery change event handler instead of javascript onchange attribute. Using this way you can fire change event on page load and set image src in page load.

$("#SelectLogo").change(function(){
  $("#logo").attr("src", '/images/'+$(":selected", this).data('img'));
}).change();

 $("#SelectLogo").change(function(){ $("#logo").attr("src", '/images/'+$(":selected", this).data('img')); console.log($("#logo").attr("src")); }).change();

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <select id="SelectLogo"> <option value="1" data-img="img1.png">Image 1</option> <option value="2" data-img="img2.png">Image 2</option> <option value="3" data-img="img3.png">Image 3</option> </select> <img id="logo" src="">