js变量undefined的判断
function adjustInputValue(loObj) {
var strDefValue = $("#" + loObj.id).attr("defValue");
if (typeof (strDefValue) == "undefined")
return true;
loObj.value = $.trim(loObj.value);
if (loObj.value == strDefValue) {
loObj.value = "";
} else if ($.zdcommon.isNull(loObj.value)) {
loObj.value = strDefValue;
}