Fetch only the `ListItemEntityTypeFullName` for list using JSOM

Question

I have a array of list names and I need to fetch ListItemEntityTypeFullName for each of the list. I can fetch the list objects. I need to know if there's any way where I can fetch only the ListItemEntityTypeFullName property for list. Is it possible? Will there be a performance improvement if all properties are fetched and if only a subset of them are fetched?

Below is my code.

var clientContext = new SP.ClientContext.get_current();
var web = clientContext.get_web();
var allLists = web.get_lists();

listnames = ["List 1", "List 2"]; // Array of list titles

var listArray = [];

for (var i = 0; i < listnames.length; i++) {
    var oList = allLists.getByTitle(listnames[i]);
    listArray.push(allLists.getByTitle(listnames[i]));
    clientContext.load(listArray[i]);

    // Throws error
    //clientContext.load(listArray[i], "Include('ListItemEntityTypeFullName')"); 
}

clientContext.executeQueryAsync(function (sender, args) {
    debugger;
    // Fetch the ListItemEntityTypeFullName by below command
    listArray[0].get_listItemEntityTypeFullName();
}, function (sender, args) {debugger});

Answer 1

May I suggest two others roads :)

1 - If my assumption about why you need the ListItemEntityTypeFullName is correct, you may not need it anymore if you change your headers in your requests. You can replace application/json;odata=verbose by application/json;odata=nometadata and never have to send the type of list item.

2 - A Rest call would be really straight forward and would actually make a simpler code : <site-uri>/_api/web/lists?$select=ListItemEntityTypeFullName&$filter=Title eq '<my-list-name' or Title eq '<my-other-list-name' will return the following json object:

{
    value: Array<{ ListItemEntityTypeFullName: string }>
}

Hope this helps!

Answer 2

Found the issue. Include is used when loading a collection. When adding individual element (list or list item) we need to directly add the property name. Below is the updated code.

clientContext.load(listArray[i], "ListItemEntityTypeFullName");