Set default contenttype on list, from JSOM

Question

I got some JavaScript that is creating some Lists and Content Types. I am able to set the Content Types on the Lists, however I am not sure how I am suppose to set it as the Default Content Type. So I am pretty much just looking for code snippet that illustrates this.

Answer 1

Default Content Type is the First Content Type in the list of content types.

You can use set_uniqueContentTypeOrder for changing the order.

var context = SP.ClientContext.get_current();
var contentTypes = context.get_web().get_lists().getByTitle('ListTitle').get_contentTypes();
var rootFolder = context.get_web().get_lists().getByTitle('ListTitle').get_rootFolder();
context.load(contentTypes);
context.load(rootFolder, 'ContentTypeOrder', 'UniqueContentTypeOrder');
context.executeQueryAsync(onSuccess, onFailed);

function onSuccess(){
    contentTypes = context.get_web().get_lists().getByTitle(current.ListTitle).get_contentTypes();
    var ctOrder = new Array();
    var enum = contentTypes.getEnumerator();
    while (enum.moveNext()) {
        //Populate ctOrder in your new order by making default content type as the first item
    }
    rootFolder.set_uniqueContentTypeOrder(ctOrder);
    rootFolder.update();
    context.executeQueryAsync(success, failed);
};

Source - https://cann0nf0dder.wordpress.com/2014/02/26/setting-default-content-types-for-listlibraries-using-javascript/