Basic ideas

Author: tshemsedinov

JavaScript/1-object.js

@@ -0,0 +1,45 @@
+'use strict';
+
+const asyncResult = () => ({
+  value: undefined,
+  onDone: null,
+  done(callback) {
+    this.onDone = callback;
+    return this;
+  },
+  resolve(value) {
+    this.value = value;
+    if (this.onDone) this.onDone(value);
+    return this;
+  }
+});
+
+// Usage
+
+const persons = {
+  10: 'Marcus Aurelius',
+  11: 'Mao Zedong',
+  12: 'Rene Descartes',
+};
+
+const getPerson = id => {
+  const result = asyncResult();
+  setTimeout(() => {
+    result.resolve({ id, name: persons[id] });
+  }, 1000);
+  return result;
+};
+
+// Subscribe
+const d1 = getPerson(10);
+d1.done(value => {
+  console.log('Resolved d1', value);
+});
+
+// Subscribe after resolve
+const d2 = getPerson(11);
+setTimeout(() => {
+  d2.done(value => {
+    console.log('Resolved d2', value);
+  });
+}, 1500);

JavaScript/2-after.js

@@ -0,0 +1,48 @@
+'use strict';
+
+const asyncResult = () => ({
+  value: undefined,
+  onDone: null,
+  resolved: false,
+  done(callback) {
+    this.onDone = callback;
+    if (this.resolved) callback(this.value);
+    return this;
+  },
+  resolve(value) {
+    this.value = value;
+    this.resolved = true;
+    if (this.onDone) this.onDone(value);
+    return this;
+  }
+});
+
+// Usage
+
+const persons = {
+  10: 'Marcus Aurelius',
+  11: 'Mao Zedong',
+  12: 'Rene Descartes',
+};
+
+const getPerson = id => {
+  const result = asyncResult();
+  setTimeout(() => {
+    result.resolve({ id, name: persons[id] });
+  }, 1000);
+  return result;
+};
+
+// Subscribe
+const d1 = getPerson(10);
+d1.done(value => {
+  console.log('Resolved d1', value);
+});
+
+// Subscribe after resolve
+const d2 = getPerson(11);
+setTimeout(() => {
+  d2.done(value => {
+    console.log('Resolved d2', value);
+  });
+}, 1500);