HigherOrderFunction Lab 8

.eslintrc.json

@@ -18,7 +18,7 @@
     ],
     "linebreak-style": [
       "error",
-      "unix"
+      "windows"
     ],
     "quotes": [
       "error",

Exercises/1-callback.js

@@ -1,5 +1,12 @@
 'use strict';
 
-const iterate = (obj, callback) => null;
-
+const iterate = (obj, callback) => {
+  for (const key in obj) {
+    callback(key, obj[key], obj);
+  }
+};
+const obj = { a: 1, b: 2, c: 3 };
+iterate(obj, (key, value) => {
+  console.log({ key, value });
+});
 module.exports = { iterate };

Exercises/2-closure.js

@@ -1,5 +1,12 @@
 'use strict';
 
-const store = x => null;
+// const store = value => {
+//   const storage = [value];
+//   return () => storage.shift();
+// };
+const store = value => () => value;
 
+const read = store(5);
+const value = read();
+console.log(value);
 module.exports = { store };

Exercises/3-wrapper.js

@@ -1,5 +1,22 @@
 'use strict';
 
-const contract = (fn, ...types) => null;
+const contract = (fn, ...types) => (...args) => {
+  for (let i = 0; i < args.length; i++) {
+    if (typeof(args[i]) !== types[i].name.toLowerCase()) throw new TypeError();
+  }
+  const res = fn(...args);
+  const resExpectedType = types.pop().name.toLowerCase();
+  if (typeof(res) !== resExpectedType) throw new TypeError();
+  return res;
+};
+
+const add = (a, b) => a + b;
+const addNumbers = contract(add, Number, Number, Number);
+const res1 = addNumbers(2, 1);
+console.dir(res1);
+const concat = (s1, s2) => s1 + s2;
+const concatStrings = contract(concat, String, String, String);
+const res2 = concatStrings('Hello ', 'world!');
+console.dir(res2);
 
 module.exports = { contract };