Sharepoint survey: Dynamically update lookup - sharepoint

Question

I currently am working on designing a Sharepoint survey.
The first question is a lookup from a list, which looks like this:
Course1
Course2
Course3
Course4
Now, the user has to select one of these answers. While I got the lookup working, I have problem in updating the list.
the idea is, that the user can add his own courses to complement the list.
So for example, he can select OTHER and type in Course5 into a textbox, which should then be added to the list. The next user should then be able to select Course5 from the drop down list.¨
I have problems writing the result of a survey into the list - is this even possible?
Kind regards.

Answer 1

In choice field, it provide the 'fill-in' feature, unfortunately, the lookup column can't provide this feature.
As a workaround, we can using jQuery append a textbox and a button in the lookup column below in the newform.aspx page. Add some text in the textbox and click the "Add" button, then add data to the lookup list. The following example for your reference:
<script type="text/javascript" src="https://code.jquery.com/jquery-1.12.4.min.js"></script>
<script type="text/javascript">
var questionTitle="question1";
var lookupListName="CL30";
$(function(){
$("select[title='"+questionTitle+"']").closest("td").append("<input id='lookupitemTitle' type='text'/> <input id='addlookupitembtn' type='button' value='Add'>");
$("#addlookupitembtn").click(function(){
if($("#lookupitemTitle").val().trim()!=""){
AddListItem(lookupListName);
}
});
});
function AddListItem(listName){
var itemType = GetItemTypeForListName(listName);
var item = {
"__metadata": { "type": itemType },
"Title": $("#lookupitemTitle").val()
};
$.ajax({
url: _spPageContextInfo.siteAbsoluteUrl + "/_api/web/lists/getbytitle('" + listName + "')/items",
type: "POST",
contentType: "application/json;odata=verbose",
data: JSON.stringify(item),
headers: {
"Accept": "application/json;odata=verbose",
"X-RequestDigest": $("#__REQUESTDIGEST").val()
},
success: function (data) {
var item=data.d;
$("select[title='"+questionTitle+"']").append("<option selected='selected' value='"+item.ID+"'>"+item.Title+"</option>");
},
error: function (data) {
alert("Error");
}
});
}
function GetItemTypeForListName(name) {
return "SP.Data." + name.charAt(0).toUpperCase() + name.split(" ").join("").slice(1) + "ListItem";
}
</script>