Code for value assignment of CheckBox, RadioButton, and DropDownList in Jquery

The Jquery version is updated quickly, and the code writing has changed a lot. The following Jquery Code applies to query1.4 and later versions.
Radio

1. To obtain the selected value, you can use either of the following methods:
$ ('Input: radio: checked'). val ();
$ ("Input [type = 'Radio ']: checked"). val ();
$ ("Input [name = 'rd']: checked"). val ();
2. Set the first Radio as the selected value:
$ ('Input: radio: first '). attr ('checked', 'checked ');
Or
$ ('Input: radio: first '). attr ('checked', 'true ');
Note: attr ("checked", 'checked') = attr ("checked", 'true') = attr ("checked", true)
3. Set the last Radio as the selected value:
$ ('Input: radio: la'). attr ('checked', 'checked ');
Or
$ ('Input: radio: la'). attr ('checked', 'true ');
4. Set any radio as the selected value based on the index value:
$ ('Input: radio '). eq (index value). attr ('checked', 'true'); index value = 0, 1, 2 ....
Or
$ ('Input: radio '). slice (1, 2). attr ('checked', 'true ');
5. Set Radio as the selected Value based on the Value.
$ ("Input: radio [value = 'rd2 ']"). attr ('checked', 'true ');
Or
$ ("Input [value = 'rd2 ']"). attr ('checked', 'true ');
6. Delete Radio whose Value is rd2.
$ ("Input: radio [value = 'rd2 ']"). remove ();
7. Delete the Radio numbers
$ ("Input: radio"). eq (index value). remove (); index value = 0, 1, 2 ....
For example, delete 3rd Radio: $ ("input: radio"). eq (2). remove ();
8. Traverse Radio
$ ('Input: radio '). each (function (index, domEle ){
// Write code
});
DropDownList

1. Obtain the selected items:
Obtain the Value of the selected item:
$ ('Select # sel option: selected'). val ();
Or
$ ('Select # sel '). find ('option: selected'). val ();
Obtain the Text value of the selected item:
$ ('Select # seloption: selected'). text ();
Or
$ ('Select # sel '). find ('option: selected'). text ();
2. Obtain the index value of the selected item:
$ ('Select # sel '). get (0). selectedIndex;
3. obtain the maximum index value of the current option:
$ ('Select # sel option: la'). attr ("index ")
4. Get the DropdownList length:
$ ('Select # sel ') [0]. options. length;
Or
$ ('Select # sel '). get (0). options. length;
5. Set the first option to the selected value:
$ ('Select # sel option: first '). attr ('selected', 'true ')
Or
$ ('Select # sel ') [0]. selectedIndex = 0;
6. Set the last option to the selected value:
$ ('Select # sel option: last). attr ('selected', 'true ')
7. set any option as the selected value based on the index value:
$ ('Select # sel ') [0]. selectedIndex = index value; index value = 0, 1, 2 ....
8. Set option of Value = 4 to the selected Value:
$ ('Select # sel '). attr ('value', '4 ');
Or
$ ("Select # sel option [value = '4']"). attr ('selected', 'true ');
9. delete option with Value = 3:
$ ("Select # sel option [value = '3']"). remove ();
10. Delete the following options:
$ ("Select # sel option"). eq (index value). remove (); index value = 0, 1, 2 ....
For example, delete 3rd Radio entries:
$ ("Select # sel option"). eq (2). remove ();
11. Delete the first option:
$ ("Select # sel option"). eq (0). remove ();
Or
$ ("Select # sel option: first"). remove ();
12. Delete the last option:
$ ("Select # sel option: last"). remove ();
13. Delete dropdownlist:
$ ("Select # sel"). remove ();
14. Add an option after select:
$ ("Select # sel"). append ("<option value = '6'> f </option> ");
15. Add an option before select:
$ ("Select # sel"). prepend ("<option value = '0'> 0 </option> ");
16. Traverse option:
$ ('Select # sel option '). each (function (index, domEle ){
// Write code
});
CheckBox
1. Obtain the selected items of a single checkbox (three methods ):
$ ("Input: checkbox: checked"). val ()
Or
$ ("Input: [type = 'checkbox']: checked"). val ();
Or
$ ("Input: [name = 'ck ']: checked"). val ();
2. Obtain multiple checkbox selected items:
$ ('Input: checkbox'). each (function (){
If ($ (this). attr ('checked') = true ){
Alert ($ (this). val ());
}
});
3. Set the first checkbox as the selected value:
$ ('Input: checkbox: first '). attr ("checked", 'checked ');
Or
$ ('Input: checkbox'). eq (0). attr ("checked", 'true ');
4. Set the last checkbox as the selected value:
$ ('Input: radio: la'). attr ('checked', 'checked ');
Or
$ ('Input: radio: la'). attr ('checked', 'true ');
5. set any checkbox as the selected value based on the index value:
$ ('Input: checkbox). eq (index value). attr ('checked', 'true'); index value = 0, 1, 2 ....
Or
$ ('Input: radio '). slice (1, 2). attr ('checked', 'true ');
6. Select multiple checkboxes:
Select 1st and 2nd checkboxes at the same time:
$ ('Input: radio '). slice (). attr ('checked', 'true ');
7. Set checkbox as the selected Value based on the Value:
$ ("Input: checkbox [value = '1']"). attr ('checked', 'true ');
8. Delete the checkbox with Value = 1:
$ ("Input: checkbox [value = '1']"). remove ();
9. Delete the following checkboxes:
$ ("Input: checkbox"). eq (index value). remove (); index value = 0, 1, 2 ....
For example, delete 3rd checkboxes:
$ ("Input: checkbox"). eq (2). remove ();
10. traverse the checkbox:
$ ('Input: checkbox'). each (function (index, domEle ){
// Write code
});
11. Select All
$ ('Input: checkbox'). each (function (){
$ (This). attr ('checked', true );
});
12. deselect all options:
$ ('Input: checkbox'). each (function (){
$ (This). attr ('checked', false );
});