Get the selected item in a drop down dynamically

Actually I forgot to add this topic. I think this is the topic to discuss first. Anyway this post will tell you how to get the selected item, the selected value in a set of options of a select input field of an HTML form. The value is accessed or retrieved using java script or jquery API. The code is below.

java script code : 

document.getElementById("SELECT_ID").value;

jquery code :

$("#SELECT_ID").val();

For eg:-

If the HTML code is as below then the code will be as explained below,

<select name="sel_name" id="sel_id">

<option value="I will help you">I will help you</option>

<option value="I will not help you">I will not help you</option>

<option value="I can assist you">I can assist you</option>

<option value="I cant assist you">I cant assist you</option>

</select>

Then the java script code to dynamically pick the selected option is,

document.getElementById("sel_id").value;

and the jquery code for the same is,

$("#sel_id").val();

Remove an option dynamically from Drop down or list using javascript and jquery

If there is a requirement to delete an existing option from a select input field in a form dynamically,  that can be a list box or combo, i.e drop down type of select. You can dynamically remove an option from it using java script or jquery using the following code snippet. The id selector is used here, if you wish you can use other selectors also. To remove an option from select, the following java script can be used,

document.getElementById('SELECT_ID').remove(option_index);

the same can be achieved using the following jquery snippet,

$("#SELECT_ID option[value='OPTION_VALUE']").remove();

For eg:- if the html code for the select is like this,

<select id='myselect'>
<option value="I loves Linux">I loves Linux</option>
<option value="I use windows too">I use windows too</option>
<option value="Linux is free software">Linux is free software</option>
<option value="Java script is simple">Java script is simple</option>
</select>

then the java script code to remove the option 'I use windows too' will be,

document.getElementById('myselect').remove(1); //it is 1 because the index start from 0

using jquery,

$("#myselect option[value='I use windows too']").remove();

To get the number of items in a drop down dynamically

Sometimes you will be required to count the number of options in a select (list/drop down) dynamically. You can achieve this using the following java script or jquery code snippet. This will give you the total number of options in select input field in a form, that having a unique id. You can use other selectors instead of id based selection. The number of options in a drop down (combo box/list box) can be achieved using the following javascript code snippet,

document.getElementById('SELECT_ID').options.length;

using jquery we can achieve the same as,

$("#SELECT_ID").attr('options').length;

For eg:- if the html code for the select is like this

<select id="myselect">

<option value="I want sleep" >I want sleep</option>

<option value="I want go" >I want go</option>

<option value="I can drive" >I can drive</option>

<option value="I can code" >I can code</option>

</select>

then the javascript code will be,

document.getElementById('myselect').options.length;

using jquery we can achieve the same as,

$("#myselect").attr('options').length;

Add a new option to drop down using java script and jquery

Sometimes the developer will need to add a new option to the select (drop down/list) dynamically. You can achieve this by using java script or jquery. The below code will add a new option to the existing select input field. The id of the select is the selector used in the case, you can use other selectors too.To add a new option dynamically to drop down the following java script code can be used,

var newoption = document.createElement("OPTION");
        newoption .text = 'Option_display_text';
        newoption .value = 'Option_value';
        document.getElementById('DROPDOWN_ID').options.add(newoption ); 

same can be achieved using jquery using this snippet,

$("#DROPDOWN_ID").append('<option value="Option_value">Option_display_text</option>');

For e.g:- if the html for select (drop down) is like this,

<select id="country">

<option value="India" >India</option>

<option value="KSA" >KSA</option>

<option value="UK" >UK</option>

<option value="USA" >USA</option>

</select>

to insert a new option quatar then the javascript code will look like this,

var newoption = document.createElement("OPTION");
        newoption .text = 'quatar';
        newoption .value = 'quatar';
        document.getElementById('country').options.add(newoption );

and in jquery it is like this,

$("#country").append('<option value="Quatar">Quatar</option>');