Add repeatGenerator

snippets/repeatGenerator.md

@@ -0,0 +1,27 @@
+---
+title: repeatGenerator
+tags: function,generator,advanced
+---
+
+Creates a generator, repeating the given value indefinitely.
+
+- Use a non-terminating `while` loop, that will `yield` a value every time `Generator.prototype.next()` is called.
+- Use the return value of the `yield` statement to update the returned value if the passed value is not `undefined`.
+
+```js
+const repeatGenerator = function* (val) {
+  let v = val;
+  while (true) {
+    let newV = yield v;
+    if (newV !== undefined) v = newV;
+  }
+};
+```
+
+```js
+const repeater = repeatGenerator(5);
+repeater.next(); // { value: 5, done: false }
+repeater.next(); // { value: 5, done: false }
+repeater.next(4); // { value: 4, done: false }
+repeater.next(); // { value: 4, done: false }
+```