Task Queue Utility

examples/taskqueuer.js

@@ -0,0 +1,40 @@
+/*
+ * This examples show the usage of the task queue class in order to help
+ * make your code look cleaner when running lots of nested async tasks.
+ *
+ * This is helpful to preventing "pyramid of doom"-style callback nesting.
+ */
+const mineflayer = require('mineflayer')
+
+if (process.argv.length < 4 || process.argv.length > 6) {
+  console.log('Usage : node taskqueuer.js <host> <port> [<name>] [<password>]')
+  process.exit(1)
+}
+
+const bot = mineflayer.createBot({
+  host: process.argv[2],
+  port: parseInt(process.argv[3]),
+  username: process.argv[4] ? process.argv[4] : 'TaskQueueBot',
+  password: process.argv[5]
+})
+
+bot.on('spawn', () => {
+  const queue = new mineflayer.TaskQueue()
+  const entity = bot.player.entity
+
+  // Through the use of a task queuer, we can add a lot of nested actions to the queue
+  // Each task is called inside the callback of the previous task.
+
+  queue.add(cb => setTimeout(cb, 5000)) // Works on any async function
+  queue.addSync(() => bot.chat('Going to mine down 10 blocks')) // Support for sync functions, too.
+
+  for (let i = 1; i <= 10; i++) {
+    queue.add(cb => setTimeout(cb, 1000))
+    queue.add(cb => bot.dig(bot.blockAt(entity.position.offset(0, -1, 0)), cb)) // Make sure to pass the cb into the callback!
+    queue.add(cb => setTimeout(cb, 50))
+    queue.addSync(() => bot.chat(`Mined block ${i}`))
+  }
+
+  // After making the queue, call 'runAll' to execute it. You can add an optional callback when it's done.
+  queue.runAll(() => bot.chat('All done!'))
+})

index.d.ts

@@ -768,3 +768,10 @@ export var supportedVersions: Array<string>;
 export var testedVersions: Array<string>;
 
 export function supportFeature(feature: string, version: string): boolean;
+
+export class TaskQueue {
+  stopOnError: boolean;
+  add(cb: (cb: () => void) => void): void;
+  addSync(cb: () => void): void;
+  runAll(cb: (err?: Error) => void): void;
+}

index.js

@@ -48,6 +48,7 @@ module.exports = {
   Dispenser: require('./lib/dispenser'),
   EnchantmentTable: require('./lib/enchantment_table'),
   ScoreBoard: require('./lib/scoreboard'),
+  TaskQueue: require('./lib/taskqueue'),
   BossBar: require('./lib/bossbar'),
   supportedVersions,
   testedVersions,

lib/taskqueue.js

@@ -0,0 +1,74 @@
+/**
+ * A utility class for queuing up a set of actions to preform asynchronously.
+ */
+class TaskQueue {
+  constructor () {
+    this._tasks = []
+    this.stopOnError = true
+  }
+
+  /**
+   * Adds a new task to the end of this task queue.
+   *
+   * @param task - The async task to run.
+   */
+  add (task) {
+    this._tasks.push(task)
+  }
+
+  /**
+   * Adds a new sync task to the end of this task queue.
+   *
+   * @param task - The sync task to run.
+   */
+  addSync (task) {
+    this._tasks.push(cb => {
+      try {
+        task()
+      } catch (err) {
+        cb(err)
+        return
+      }
+
+      cb()
+    })
+  }
+
+  /**
+   * Runs all tasks currently in this queue and empties the queue.
+   *
+   * @param cb - The optional callback to run when all tasks are finished.
+   */
+  runAll (cb) {
+    const taskList = this._tasks
+    this._tasks = []
+
+    if (!cb) cb = () => {}
+
+    let index = -1
+    const runNext = () => {
+      index++
+      if (index >= taskList.length) {
+        cb()
+        return
+      }
+
+      try {
+        taskList[index](err => {
+          if (err) {
+            cb(err)
+            if (this.stopOnError) return
+          }
+
+          runNext()
+        })
+      } catch (err) {
+        cb(err)
+      }
+    }
+
+    runNext()
+  }
+}
+
+module.exports = TaskQueue