Jquery operates drop-down box (DropDownList) to implement value assignment_jquery

1. Get the selected item:

Copy code The code is as follows:

Get the Value of the selected item ：
$('select#sel option:selected').val();
or
$('select#sel').find('option:selected').val();
Get the Text value of the selected item:
$('select#seloption:selected').text();
or
$('select#sel').find('option:selected' ).text();

2. Get the index value of the currently selected item:

Copy code The code is as follows:

$('select#sel').get(0).selectedIndex;

3. Get the maximum index value of the current option:

Copy code The code is as follows:

$('select#sel option:last').attr( "index")

4. Get the length of DropdownList:

Copy code The code is as follows:

$('select#sel')[0].options.length;
or
$('select#sel').get(0).options.length;

5. Set the first option to the selected value:

Copy the code The code is as follows:

$('select#sel option:first').attr('selected','true')
or
$('select#sel')[0].selectedIndex = 0;

6. Set the last option to the selected value:

Copy code The code is as follows:

$('select#sel option:last).attr('selected','true')

7. Set any option to be selected based on the index value Value:

Copy code The code is as follows:

$('select#sel')[0 ].selectedIndex = index value; index value = 0,1,2....

8. Set the option of Value=4 to the selected value:

Copy code The code is as follows:

$('select#sel').attr('value','4');
Or
$("select#sel option[value='4']").attr('selected', 'true');

9. Delete option with Value=3 :

Copy code The code is as follows:

$("select#sel option[value=' 3']").remove();

10. Delete which option:

Copy code The code is as follows:

$(" select#sel option ").eq(index value).remove(); index value=0,1,2....
For example, delete the third Radio:
$(" select#sel option ").eq(2).remove();

11. Delete the first option:

Copy code The code is as follows:

$(" select#sel option ").eq(0).remove ();
or
$("select#sel option:first").remove();

12. Delete the last option:

Copy code The code is as follows:

$("select#sel option:last").remove();

13. Delete dropdownlist:

Copy code The code is as follows:

$( "select#sel").remove();

14. Add an option after select:

Copy code The code is as follows:

$("select#sel").append("f");

15. Add an option in front of select:

Copy code The code is as follows:

$("select#sel").prepend("0");

16. Traverse options:

Copy code The code is as follows:

$(' select #sel option ').each(function (index, domEle) {
//Write code
});