How can I get ID when I insert new items to list?

Question

I'm currently using JSOM to insert new items to list.

   var clientContext = new SP.ClientContext();
    var oWeb = clientContext.get_web();
    var oList = oWeb.get_lists().getByTitle("request");
    var camlQuery = new SP.CamlQuery();
    var oListItemCreationInformation = new SP.ListItemCreationInformation();
    var oListItem = oList.addItem(oListItemCreationInformation);

    oListItem.set_item('formType', ftype);
oListItem.update();
    clientContext.load(oListItem);
    clientContext.executeQueryAsync(onsuccess(), onfailed);

}
function onsuccess() {
    alert("Success");
    console.log( oListItem.get_id());
    
}

As I expected it will return the new item ID, but it only return -1.

What can I do to get the correct ID in order to help adding upload file to list function to my page?

Answer 1

Try defining define oListItem as a global variable like below:

var oListItem;

function insertListItem() {
    var clientContext = new SP.ClientContext();
    var oWeb = clientContext.get_web();
    var oList = oWeb.get_lists().getByTitle("request");
    var camlQuery = new SP.CamlQuery();
    var oListItemCreationInformation = new SP.ListItemCreationInformation();
    oListItem = oList.addItem(oListItemCreationInformation);

    oListItem.set_item('formType', ftype);
    oListItem.update();
    clientContext.load(oListItem);
    clientContext.executeQueryAsync(onsuccess, onfailed);
}
function onsuccess(sender, args) {
    alert("Success");
    console.log(oListItem.get_id());
}

OR

Try using an inline function instead of a named function for the success handler. That way you will not need to add a global variable.

clientContext.executeQueryAsync(
    function (sender, args) {
        var itemId = oListItem.get_id();
        console.log(itemId);
    },
    function (sender, args) {
        alert("failed");
    }
);

Source: Get ID after inserting Item into SharePoint 2013 Host Web List