1.判斷select選項(xiàng)中 是否存在Value="paraValue"的Item

function jsSelectIsExitItem(objSelect, objItemValue) {        
    var isExit = false;        
    for (var i = 0; i < objSelect.options.length; i++) {        
        if (objSelect.options[i].value == objItemValue) {        
            isExit = true;        
            break;        
        }        
    }        
    return isExit;        
} 

2.向select選項(xiàng)中 加入一個(gè)Item

function jsAddItemToSelect(objSelect, objItemText, objItemValue) {        
    //判斷是否存在        
    if (jsSelectIsExitItem(objSelect, objItemValue)) {        
        alert("該Item的Value值已經(jīng)存在");        
    } else {        
        var varItem = new Option(objItemText, objItemValue);      
        objSelect.options.add(varItem);     
        alert("成功加入");     
    }        
} 

3.從select選項(xiàng)中 刪除一個(gè)Item

function jsRemoveItemFromSelect(objSelect, objItemValue) {        
    //判斷是否存在        
    if (jsSelectIsExitItem(objSelect, objItemValue)) {        
        for (var i = 0; i < objSelect.options.length; i++) {        
            if (objSelect.options[i].value == objItemValue) {        
                objSelect.options.remove(i);        
                break;        
            }        
        }        
        alert("成功刪除");        
    } else {        
        alert("該select中 不存在該項(xiàng)");        
    }        
} 

4.刪除select中選中的項(xiàng)

function jsRemoveSelectedItemFromSelect(objSelect) {        
    var length = objSelect.options.length - 1;    
    for(var i = length; i >= 0; i--){    
        if(objSelect[i].selected == true){    
            objSelect.options[i] = null;    
        }    
    }    
}

5.修改select選項(xiàng)中 value="paraValue"的text為"paraText"

function jsUpdateItemToSelect(objSelect, objItemText, objItemValue) {        
    //判斷是否存在        
    if (jsSelectIsExitItem(objSelect, objItemValue)) {        
        for (var i = 0; i < objSelect.options.length; i++) {        
            if (objSelect.options[i].value == objItemValue) {        
                objSelect.options[i].text = objItemText;        
                break;        
            }        
        }        
        alert("成功修改");        
    } else {        
        alert("該select中 不存在該項(xiàng)");        
    }        
} 

6.設(shè)置select中text="paraText"的第一個(gè)Item為選中

function jsSelectItemByValue(objSelect, objItemText) {            
    //判斷是否存在        
    var isExit = false;        
    for (var i = 0; i < objSelect.options.length; i++) {        
        if (objSelect.options[i].text == objItemText) {        
            objSelect.options[i].selected = true;        
            isExit = true;        
            break;        
        }        
    }              
    //Show出結(jié)果        
    if (isExit) {        
        alert("成功選中");        
    } else {        
        alert("該select中 不存在該項(xiàng)"); 
    }        
}

7.設(shè)置select中value="paraValue"的Item為選中

objSelect.value = objItemValue;

8.得到select的當(dāng)前選中項(xiàng)的value

var currSelectValue = objSelect.value;

9.得到select的當(dāng)前選中項(xiàng)的text

var currSelectText = objSelect.options[objSelect.selectedIndex].text;

10.得到select的當(dāng)前選中項(xiàng)的Index

var currSelectIndex = objSelect.selectedIndex;

11.清空select的項(xiàng)

objSelect.options.length = 0;