select 下拉框 设置值

        function setSelectOption(objSelect, targetValue){
            if(objSelect){
                var options = objSelect.options;
                if(options){
                    var len = options.length;
                    for(var i=0;i<len;i++){
                        if(options[i].value == targetValue){
                            options[i].defaultSelected = true;
                            options[i].selected = true;
                            return true;
                        }
                    }
                } else {
                    alert('missing element(s)!');
                }
            } else {
                alert('missing element(s)!');
            }
        }