# Editor example Ajax override - using localStorage for the data source

This example shows how the `ajax` initialisation option can be used to replace the default Ajax call that Editor makes and instead use the browser's `localStorage` abilities to save the state of the table locally on the browser. This means that the user effectively has persistent storage, but it is available only to them on their current browser.

The code in this example shows the `ajax` option as a function that implements everything that is required by Editor for data storage and retrieval. The 'create', 'edit' and 'remove' actions are each handled by storing the submitted data in a local variable, which is then stored in local storage for data persistence.

Note that this example fully supports Editor's multi-row editing capability as it fully implements the client / server data interchange format Editor uses.

Although this particular use case is fairly limited, it does show how Editor's `ajax` option can be used to intercept and manage the data requests that Editor makes. Expanding on this almost any data storage system could be used from Firebase to WebSockets.

Item | Status
--- | ---
Item | Status

- Javascript
- HTML
- CSS
- Ajax
- Server-side script

The Javascript shown below is used to initialise the table shown in this example:

`var editor; // use a global for the submit and return data rendering in the examples $(document).ready(function() { // Object that will contain the local state var todo = {}; // Create or update the todo localStorage entry if ( localStorage.getItem('todo') ) { todo = JSON.parse( localStorage.getItem('todo') ); } // Set up the editor editor = new $.fn.dataTable.Editor( { table: "#example", fields: [ { label: "Item:", name: "item" }, { label: "Status:", name: "status", type: "radio", def: "To do", options: [ 'To do', 'Done' ] } ], ajax: function ( method, url, d, successCallback, errorCallback ) { var output = { data: [] }; if ( d.action === 'create' ) { // Create new row(s), using the current time and loop index as // the row id var dateKey = +new Date(); $.each( d.data, function (key, value) { var id = dateKey+''+key; value.DT_RowId = id; todo[ id ] = value; output.data.push( value ); } ); } else if ( d.action === 'edit' ) { // Update each edited item with the data submitted $.each( d.data, function (id, value) { value.DT_RowId = id; $.extend( todo[ id ], value ); output.data.push( todo[ id ] ); } ); } else if ( d.action === 'remove' ) { // Remove items from the object $.each( d.data, function (id) { delete todo[ id ]; } ); } // Store the latest `todo` object for next reload localStorage.setItem( 'todo', JSON.stringify(todo) ); // Show Editor what has changed successCallback( output ); } } ); // Initialise the DataTable $('#example').DataTable( { dom: "Bfrtip", data: $.map( todo, function (value, key) { return value; } ), columns: [ { data: "item" }, { data: "status" } ], select: true, buttons: [ { extend: "create", editor: editor }, { extend: "edit", editor: editor }, { extend: "remove", editor: editor } ] } ); } );`

In addition to the above code, the following Javascript library files are loaded for use in this example:

- https://code.jquery.com/jquery-3.3.1.js
- https://cdn.datatables.net/1.10.20/js/jquery.dataTables.min.js
- https://cdn.datatables.net/buttons/1.6.0/js/dataTables.buttons.min.js
- https://cdn.datatables.net/select/1.3.1/js/dataTables.select.min.js
- ../../js/dataTables.editor.min.js

The HTML shown below is the raw HTML table element, before it has been enhanced by DataTables:

This example uses a little bit of additional CSS beyond what is loaded from the library files (below), in order to correctly display the table. The additional CSS used is shown below:

``

The following CSS library files are loaded for use in this example to provide the styling of the table:

- https://cdn.datatables.net/1.10.20/css/jquery.dataTables.min.css
- https://cdn.datatables.net/buttons/1.6.0/css/buttons.dataTables.min.css
- https://cdn.datatables.net/select/1.3.1/css/select.dataTables.min.css
- ../../css/editor.dataTables.min.css

This table loads data by Ajax. The latest data that has been loaded is shown below. This data will update automatically as any additional data is loaded.

The script used to perform the server-side processing for this table is shown below. Please note that this is just an example script using PHP. Server-side processing scripts can be written in any language, using the protocol described in the DataTables documentation.