Feature: add server-sent events support

src/app.ts

@@ -8,14 +8,15 @@ import { Low } from 'lowdb'
 import { json } from 'milliparsec'
 import sirv from 'sirv'
 
-import { Data, isItem, Service } from './service.js'
+import { Data, isItem, Item, Service } from './service.js'
 
 const __dirname = dirname(fileURLToPath(import.meta.url))
 const isProduction = process.env['NODE_ENV'] === 'production'
 
 export type AppOptions = {
   logger?: boolean
   static?: string[]
+  chunk?: number
 }
 
 const eta = new Eta({
@@ -75,6 +76,32 @@ export function createApp(db: Low<Data>, options: AppOptions = {}) {
     next?.()
   })
 
+  app.get('/sse/:name', (req, res) => {
+    res.header('Content-Type', 'text/event-stream');
+    const { name = '' } = req.params
+
+    const interval = 200;
+
+    const data = service.find(name) as Item[];
+    if (!data.length) {
+      return res.sendStatus(404)
+    }
+
+    for (let i = 0; i < data.length; i += options.chunk!) {
+      setTimeout(() => {
+        const payload = JSON.stringify(data.slice(i, options.chunk! + i))
+        res.write(`data: ${payload}\n\n`);
+        res.flushHeaders();
+
+        if (i >= data.length) {
+          res.end();
+        }
+      }, i * interval);
+    }
+
+    return;
+  })
+
   app.get('/:name/:id', (req, res, next) => {
     const { name = '', id = '' } = req.params
     res.locals['data'] = service.findById(name, id, req.query)

src/bin.ts

@@ -22,6 +22,7 @@ Options:
   -p, --port <port>  Port (default: 3000)
   -h, --host <host>  Host (default: localhost)
   -s, --static <dir> Static files directory (multiple allowed)
+  --chunk <size> Server-sent events chunk size (default: 2)
   --help             Show this message
   --version          Show version number
 `)
@@ -33,6 +34,7 @@ function args(): {
   port: number
   host: string
   static: string[]
+  chunk: number
 } {
   try {
     const { values, positionals } = parseArgs({
@@ -53,6 +55,10 @@ function args(): {
           multiple: true,
           default: [],
         },
+        chunk: {
+          type: 'string',
+          default: '2'
+        },
         help: {
           type: 'boolean',
         },
@@ -100,6 +106,7 @@ function args(): {
       port: parseInt(values.port as string),
       host: values.host as string,
       static: values.static as string[],
+      chunk: parseInt(values.chunk as string),
     }
   } catch (e) {
     if ((e as NodeJS.ErrnoException).code === 'ERR_PARSE_ARGS_UNKNOWN_OPTION') {
@@ -112,7 +119,7 @@ function args(): {
   }
 }
 
-const { file, port, host, static: staticArr } = args()
+const { file, port, host, static: staticArr, chunk } = args()
 
 if (!existsSync(file)) {
   console.log(chalk.red(`File ${file} not found`))
@@ -140,7 +147,7 @@ const db = new Low<Data>(observer, {})
 await db.read()
 
 // Create app
-const app = createApp(db, { logger: false, static: staticArr })
+const app = createApp(db, { logger: false, static: staticArr, chunk })
 
 function logRoutes(data: Data) {
   console.log(chalk.bold('Endpoints:'))