SharePoint learning notes-ecmascript object model series-7. Get and modify the lookup field of the List

Previously we mentioned how to use the ecmascript object model to operate ordinary list items. But if the list we operate contains a lookup field, what should we do?
First, refer to this article to build our testing environment.
SharePoint Study Notes --- splist -- create a list with the lookup field

1. For the get operation, we use the followingCode

<SCRIPT type = "text/JavaScript">
Function Getlookupvalue (){
VaR Context = New Sp. clientcontext. get_current ();
VaR Web = context. get_web ();
VaR List = web. get_lists (). getbytitle ('testsale ');
VaR Query = sp. camlquery. createallitemsquery ();
Allitems = List. getitems (query );
Context. Load (allitems, 'include (productname, lookupstaffname )');
Context.exe cutequeryasync (function. createdelegate ( This , This . Successgetlookupvalue ),
Function. createdelegate ( This , This . Failedgetlookupvalue ));
}

Function Successgetlookupvalue (){
VaR Textfiled = "";
VaR Listenumerator = This . Allitems. getenumerator ();
While (Listenumerator. movenext ()){
VaR Currentitem = listenumerator. get_current ();
Textfiled + = currentitem. get_item ('productname ') +'-'+ currentitem. get_item ('lookupstaffname'). get_lookupvalue () +' \ n ';
}
Alert (textfiled );
}

FunctionFailedgetlookupvalue (sender, argS ){
Alert ("failed. message:" + args. get_message ());
}

</SCRIPT>

The effect is as follows:

2. For the modification operation, we use the following code:

<SCRIPT type = "text/JavaScript">
Function Setlookupvalue (){
VaR Context = New Sp. clientcontext. get_current ();
VaR Web = context. get_web ();
VaR List = web. get_lists (). getbytitle ('testsale ');
VaR Query = sp. camlquery. createallitemsquery ();
Allitems = List. getitems (query );
Context. Load (allitems, 'include (productname, lookupstaffname )');
Context.exe cutequeryasync (function. createdelegate ( This , This . Successsetlookupvalue), function. createdelegate ( This , This . Failedsetlookupvalue ));
}
Function Successsetlookupvalue (){
VaR Textfiled = ""
VaR Listenumerator = This . Allitems. getenumerator ();
While (Listenumerator. movenext ()){
VaR Currentitem = listenumerator. get_current ();
VaR Newlookupfield = New Sp. fieldlookupvalue ();

Newlookupfield. set_lookupid (2) // Updated with some lookup value for lookupstaffname Column
// Here is an ID of your lookup list item 'Steve ';
Currentitem. set_item ('lookupstaffname', newlookupfield );
Currentitem. Update ();
// Call context.exe cutequeryasync again
}
}
Function Failedsetlookupvalue (sender, argS ){
Alert ("failed. message:" + args. get_message ());
}

</SCRIPT>

The effect is as follows:

 

It should be noted that in the modification, we use the code

Newlookupfield. set_lookupid (2)

The parameter meaning in this Code is to take the value from the list of data sources bound to lookupitem, for example: