Initial commit

shared/event.js

@@ -0,0 +1,42 @@
+export class EventBus {
+  constructor() {
+    this.map = new Map()
+  }
+
+  on(type, cb) {
+    if (this.map.has(type)) {
+      this.map.get(type).push(cb)
+    } else {
+      this.map.set(type, [cb])
+    }
+  }
+
+  off(type, cb) {
+    if (type) {
+      if (cb) {
+        const cbs = this.map.get(type)
+
+        if (!cbs) return
+        const index = cbs.findIndex((i) => i === cb)
+
+        if (index >= 0) {
+          cbs.splice(index, 1)
+        }
+      } else {
+        this.map.delete(type)
+      }
+    } else {
+      this.map.clear()
+    }
+  }
+
+  emit(type, ...args) {
+    for (let cb of this.map.get(type) ? this.map.get(type) : []) {
+      cb && cb(...args)
+    }
+  }
+
+  count(type) {
+    return this.map.get(type) ? this.map.get(type).length : 0
+  }
+}