Jquery operation select

1. determine whether the select option contains Item $ ("# selectid option [@ Value = 'paravalue ']") of value = "paraValue". length> 02. add an Item $ ("# selectid") to the select option "). append ("<option value =''> 1111 <option> "); 3. delete an Item $ ("# selectid") from the select option "). remove ("<option value =''> 1111 <option> "); 4. in the select option, set the text of value = "paraValue" to "paraText" $ ("# selectid option: selected "). attr ("value", "paraValue "). attr ("text", "paraText"); 5. set the first Item of text = "paraText" in the select statement to $ ("# selectid option [@ text = 'paratext ']"). attr ("selected", "true") 6. set the Item of value = "paraValue" in select to $ ("# selectid option [@ value = 'paravalue ']"). attr ("selected", "true") 7. set the first Item in select to select $ ("# selectid option "). eq (0 ). attr ('selected', 'true'); 8. obtain the value $ ("# selectid") of the selected item "). val (); 9. get the text $ ("# selectid") of the selected item "). text (); 10. obtain the Index document of the selected item in the select statement. getElementById ("select1 "). selectedIndex; $ ("# selectid "). get (0 ). selectedIndex11. clear select items $ ("# selectid "). empty (); JS version: // 1. determine whether the select option contains the Item function jsSelectIsExitItem (objSelect, objItemValue) {var isExit = false; for (var I = 0; I; I ++) of Value = "paraValue) {if (objSelect. options [I]. value = objItemValue) {isExit = true; break;} return isExit;} // 2. add an Item function jsAddItemToSelect (objSelect, objItemText, objItemValue, objItemPos) to the select option {// determine if (jsSelectIsExitItem (objSelect, objItemValue )) {alert ("the Value of this Item already exists");} else {var varItem = new Option (objItemText, objItemValue); // objSelect. options [objSelect. options. length] = varItem; objSelect. options. add (varItem, objItemPos); alert ("successfully added") ;}}// 3. delete an Item function jsRemoveItemFromSelect (objSelect, objItemValue) from the select option {// determine whether if (jsSelectIsExitItem (objSelect, objItemValue) {for (var I = 0; I; I ++) {if (objSelect. options [I]. value = objItemValue) {objSelect. options. remove (I); break ;}} alert ("deleted successfully") ;}else {alert ("this select does not exist") ;}} // 4. modify the text of value = "paraValue" in the select option to "paraText" function jsUpdateItemToSelect (objSelect, objItemText, objItemValue) {// determine if (jsSelectIsExitItem (objSelect, objItemValue )) {for (var I = 0; I; I ++) {if (objSelect. options [I]. value = objItemValue) {objSelect. options [I]. text = objItemText; break ;}} alert ("modified successfully") ;}else {alert ("this select does not exist") ;}}// 5. set the first Item of text = "paraText" in select to the selected function jsSelectItemByValue (objSelect, objItemText) {// determine whether var isExit = false; for (var I = 0; i; I ++) {if (objSelect. options [I]. text = objItemText) {objSelect. options [I]. selected = true; isExit = true; break;} // Show the result if (isExit) {alert ("selected successfully ");} else {alert ("this select does not exist") ;}// 6. set Item of value = "paraValue" in select to selected document. all. objSelect. value = objItemValue; // 7. obtain the value var currSelectValue = document of the selected item in the select statement. all. objSelect. value; // 8. the text var currSelectText = document. all. objSelect. options [document. all. objSelect. selectedIndex]. text; // 9. the Index var currSelectIndex = document. all. objSelect. selectedIndex; // 10. clear the select item document. all. objSelect. options. length = 0;