I know this is something that has come up time and time again, but I was wondering if there was some easy way to create a script to change a particular field for all files in a folder. And then give a pointer as to how to modify this script (for non-programmers like me) to change a different field to something else (and where to find the correct names for the fields).

For example: change all "item types" to "newspaper"
and then: change all "publication" to "New York Times"

On these forums, I found the following script which is probably close to what I'm looking for.

var fieldName = "journalAbbreviation";
var oldValue = "Urban Sdd";
var newValue = "Urban Studies";

var fieldID = Zotero.ItemFields.getID(fieldName);
var s = new Zotero.Search();
s.libraryID = Zotero.Libraries.userLibraryID;
s.addCondition(fieldName, 'is', oldValue);
var ids = await s.search();
if (!ids.length) {
return "No items found";
}
await Zotero.DB.executeTransaction(async function () {
for (let id of ids) {
let item = await Zotero.Items.getAsync(id);
let mappedFieldID = Zotero.ItemFields.getFieldIDFromTypeAndBase(item.itemTypeID, fieldName);
item.setField(mappedFieldID ? mappedFieldID : fieldID, newValue);
await item.save();
}
});
return ids.length + " item(s) updated";