如何选择 <option>在按值下拉列表中，并为其分配“选定”属性？

Question

For a dropdown list ( <select> ), at some point I need to find the option with a given value and assign the selected attribute to it.

eg:

<select id="font-size">
    <option value="12">12px</option>
    <option value="13">13px</option>
    <option value="14">14px</option>
</select>

In the example above, how would I add the "selected='selected'" attribute to the option with the value 14?

Answer 1

This would do it:

$('#font-size').val(14);

NB: this sets the selected property on the required <option> element - the attribute represents the initital value of the dropdown when the page is first loaded.

Answer 2

If you need this to set the initial value when the page is loaded then use,

   $(document).ready(function() {
    $('#font-size').val(14);
   });

or else if you want it the value of which user has selected after the loading use this,

   $(document).ready(function() {
     $('#font-size').change(function() {
       alert($(this).val());
     });
   });  

Answer 3

document.getElementById("font-size").value = "14";