7.6

01.js

@@ -0,0 +1,5 @@
+var a = 1;
+var b = false;
+function sum(a, b) {
+    return a + b;
+}

01.ts

@@ -0,0 +1,9 @@
+let x: number = 1;
+let y = false;
+
+function sum(a: number,b: number): number{
+    return a + b;
+}
+
+let m: 10 | 22 | "ee";  //字面量
+let n: number | boolean;  //