JavaScript/jQuery Chat - File Attachments

The DevExtreme JavaScript Chat allows users to attach files. When this feature is activated (fileUploaderOptions.uploadFile is specified), an “Attach” button appears in the message input field, allowing users to add files to their messages.

When users attach files, each file is displayed in the input area with a file-type icon, basic details (name and size), upload status, and an option to remove files before sending.

Backend API

$(() => { const customStore = new DevExpress.data.CustomStore({ key: 'id', load: async () => messages, insert: async (message) => { messages.push(message); return message; }, }); const dataSource = new DevExpress.data.DataSource({ store: customStore, paginate: false, }); const uploadedFilesMap = new Map(); function getFileUrl(filename) { return uploadedFilesMap.get(filename); } $('#chat').dxChat({ height: 710, dataSource, reloadOnChange: false, user: currentUser, fileUploaderOptions: { uploadFile: () => {}, onUploaded({ file }) { const url = URL.createObjectURL(file); uploadedFilesMap.set(file.name, url); }, }, onMessageEntered(e) { const { message } = e; const attachmentsWithUrls = message.attachments?.map((attachment) => ({ ...attachment, url: getFileUrl(attachment.name), })); dataSource.store().push([{ type: 'insert', data: { id: new DevExpress.data.Guid(), ...message, attachments: attachmentsWithUrls, }, }]); }, onAttachmentDownloadClick(e) { const { attachment } = e; if (!attachment?.url) { return; } const link = document.createElement('a'); link.setAttribute('href', attachment.url); link.setAttribute('download', attachment.name); document.body.appendChild(link); link.click(); document.body.removeChild(link); }, }).dxChat('instance'); });

<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml" lang="en"> <head> <title>DevExtreme Demo</title> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=5.0" /> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script> <script>window.jQuery || document.write(decodeURIComponent('%3Cscript src="js/jquery.min.js"%3E%3C/script%3E'))</script> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/25.2.4/css/dx.light.css" /> <script src="js/dx.all.js?v=25.2.4"></script> <link rel="stylesheet" type="text/css" href="styles.css" /> <script src="data.js"></script> <script src="index.js"></script> </head> <body class="dx-viewport"> <div class="demo-container"> <div class="chat-container"> <div id="chat"></div> </div> </div> </body> </html>

.demo-container { min-width: 720px; } .chat-container { display: flex; flex-grow: 1; align-items: center; justify-content: center; } .dx-chat { max-width: 480px; } .caption { font-size: var(--dx-font-size-sm); font-weight: 500; } .dx-avatar { border: 1px solid var(--dx-color-border); }

You can customize the file upload process with the following fileUploaderOptions properties:

maxFileSize
Specifies maximum allowed file size.
minFileSize
Specifies minimum allowed file size.
multiple
When set to false, limits uploads to a single file.
allowedFileExtensions
Restricts accepted file types.

For the complete list of configuration options, refer to the following API section: fileUploaderOptions.

Attachment type includes name and size fields. To add custom fields (such as url in this demo), handle the onMessageEntered event and update the message object’s attachments array as needed. You can use this handler to save files to your server.

After a user sends a message, attachments appear in the corresponding message bubble. To allow users to download attachments, implement the onAttachmentDownloadClick event handler. You can define custom download logic within the handler.