How to retrieve Lookup Field via CSOM Javascript in Sharepoint 2013

The below code is used to get lookup values from lookup field

//Get LookupField value
var oLookupField = item.get_item('FieldName');
var oLookupValue = oLookupField.get_lookupValue();
var oLookupID = oLookupField.get_lookupId();


The below code is used to get lookup values from multi lookup field

//Get Multiple Lookup Field value
var oLookupField = item.get_item('FieldName');
for(var i = 0; i < oLookupField.length; i++) {
   var oLookUpColumn = oLookupField[i];
   var oLookupValue = oLookUpColumn.get_lookupValue();
   var oLookupID = oLookUpColumn.get_lookupId();
}