This is one of the socket.io methods that is not available in the v3 read API yet. If you want to load all the subcategories you can do it with a socket.io emit. See below function
async function getSubCategories(cid) { // store current loaded children let subCats = ajaxify.data.children.slice(); let newCats = []; // start from the nextSubCategory index let start = ajaxify.data.nextSubCategoryStart; do { // load the next page newCats = await socket.emit('categories.loadMoreSubCategories', { cid: cid, start: start, }); // move start to next page start += ajaxify.data.subCategoriesPerPage; // add the newly loaded children to our sub categories subCats = subCats.concat(newCats); // we are done if no new categories were loaded } while (!newCats.length); return subCats; }You can call this function on a category page and it would return all the subcategories of that category.
