Nếu thu thập dữ liệu bị ràng buộc là một mảng JavaScript, và nếu nó đưa ra một phương pháp đặt tên thêm, phương thức addItem chỉ đơn giản gọi phương pháp này để thêm một hồ sơ sản phẩm nào để thu thập dữ liệu: | Appendix D Data Control Next it checks whether the bound data collection implements the IData interface. If so it invokes the add method on the data collection to add an empty record to the collection if If the bound data collection is a JavaScript array and if it exposes a method named add the additem method simply calls this method to add an empty record to the data collection else if instanceof Array if typeof function If the bound data collection is a JavaScript array but it does not expose the add method the addItem method simply calls the add static method on the Array class to add an empty record to the data collection else if instanceof Array if typeof function else Next the additem method sets the current data index to the index of the newly added data record - 1 Finally the additem method calls the triggerChangeEvents method passing the JavaScript object that contains the old values of the dataindex canMoveNext and canMovePrevious properties to raise the appropriate events as discussed earlier oldState Listing D-14 The addItem Method function Sys Preview UI Data DataControl addItem if var oldState if continued 1367 Appendix D Data Control Listing D-14 continued else if instanceof Array if typeof function else - 1 oldState deleteCurrentItem As the name suggests the deleteCurrentltem method deletes the current data record from the bound data collection if the data control is indeed bound to a data collection. As Listing D-15 shows this method begins by invoking the prepareChange method to return the JavaScript object .
