1 files changed, 37 insertions, 0 deletions
diff --git a/typescript.html.markdown b/typescript.html.markdown
index ba4a9e71..293a4a35 100644
--- a/typescript.html.markdown
+++ b/typescript.html.markdown
@@ -223,6 +223,43 @@ moreNumbers[5] = 5; // Error, elements are read-only
 moreNumbers.push(5); // Error, no push method (because it mutates array)
 moreNumbers.length = 3; // Error, length is read-only
 numbers = moreNumbers; // Error, mutating methods are missing
+
+// Tagged Union Types for modelling state that can be in one of many shapes
+type State = 
+  | { type: "loading" }
+  | { type: "success", value: number }
+  | { type: "error", message: string };
+
+declare const state: State;
+if (state.type === "success") {
+  console.log(state.value);
+} else if (state.type === "error") {
+  console.error(state.message);
+}
+
+// Iterators and Generators
+
+// for..of statement
+// iterate over the list of values on the object being iterated
+let arrayOfAnyType = [1, "string", false];
+for (const val of arrayOfAnyType) {
+    console.log(val); // 1, "string", false
+}
+
+let list = [4, 5, 6];
+for (const i of list) {
+   console.log(i); // "4", "5", "6"
+}
+
+// for..in statement
+// iterate over the list of keys on the object being iterated
+for (const i in list) {
+   console.log(i); // "0", "1", "2",
+}
+
+
+
+
 ```
 
 ## Further Reading