# Editor example Client-side validation

Editor, in general, assumes that server-side validation of the data will be performed and the returns reported back to the client (the validation must be done at the server anyway, so this saves duplicating logic), however there are cases where performing client-side checks can be very valuable. There are a number of methods of doing this with Editor, including simply not calling the `submit()E` method when you don't want to submit the data, but this example shows how client-side validation can be achieved using the `preSubmitE` event which can be used to cancel the submit by returning `false`.

Editor provides a wide range of events which can be attached using the `on()E` API method. In this case the `preSubmitE` event is used to run a custom function just before the data is submitted to the server The `error()E` method is used to show the error message to the end user if appropriate. Note that the event handlers functions are executed in the Editor instance's scope, so API methods can accessed using the this keyword.

Name | Position | Office | Extn. | Start date | Salary
--- | --- | --- | --- | --- | ---
Name | Position | Office | Extn. | Start date | Salary

- 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() { editor = new $.fn.dataTable.Editor( { ajax: "../php/staff.php", table: "#example", fields: [ { label: "First name:", name: "first_name" }, { label: "Last name:", name: "last_name" }, { label: "Position:", name: "position" }, { label: "Office:", name: "office" }, { label: "Extension:", name: "extn" }, { label: "Start date:", name: "start_date" }, { label: "Salary:", name: "salary" } ] } ); editor.on( 'preSubmit', function ( e, o ) { if ( o.data.first_name === '' ) { this.error('first_name', 'A first name must be given'); return false; } else if ( o.data.first_name.length >= 20 ) { this.error('first_name', 'The first name length must be less that 20 characters'); return false; } // ... etc } ); $('#example').DataTable( { dom: "Tfrtip", ajax: "../php/staff.php", columns: [ { data: null, render: function ( data, type, row ) { // Combine the first and last names into a single table field return data.first_name+' '+data.last_name; } }, { data: "position" }, { data: "office" }, { data: "extn" }, { data: "start_date" }, { data: "salary", render: $.fn.dataTable.render.number( ',', '.', 0, '$' ) } ], tableTools: { sRowSelect: "os", aButtons: [ { sExtends: "editor_create", editor: editor }, { sExtends: "editor_edit", editor: editor }, { sExtends: "editor_remove", editor: editor } ] } } ); } );`

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

- ../../../../media/js/jquery.js
- ../../../../media/js/jquery.dataTables.js
- ../../../TableTools/js/dataTables.tableTools.js
- ../../js/dataTables.editor.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:

- ../../../../media/css/jquery.dataTables.css
- ../../../TableTools/css/dataTables.tableTools.css
- ../../css/dataTables.editor.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.