As per my knowledge ([]) is used in Knockout.js this is used to define the observableArray. Please find the example and link below.
// This observable array initially contains three objects var anotherObservableArray = ko.observableArray([ { name: "Bungle", type: "Bear" }, { name: "George", type: "Hippo" }, { name: "Zippy", type: "Unknown" } ]);
https://knockoutjs.com/documentation/observableArrays.html