impress/app/assets/javascripts/ajax_auth.js

(function () {
	var CSRFProtection;
	var token = $('meta[name="csrf-token"]').attr("content");
	if (token) {
		CSRFProtection = function (xhr, settings) {
			var sendToken =
				typeof settings.useCSRFProtection === "undefined" || // default to true
				settings.useCSRFProtection;
			if (sendToken) {
				xhr.setRequestHeader("X-CSRF-Token", token);
			}
		};
	} else {
		CSRFProtection = $.noop;
	}

	$.ajaxSetup({
		beforeSend: CSRFProtection,
	});
})();