done 1-3

Exercises/1-callback.js

@@ -1,5 +1,11 @@
 'use strict';
 
-const iterate = (obj, callback) => null;
+const iterate = (obj, callback) => {
+  const keys = Object.keys(obj);
+  for (const key of keys) {
+    const value = obj[key];
+    callback(key, value, obj);
+  }
+};
 
 module.exports = { iterate };

Exercises/2-closure.js

@@ -1,5 +1,5 @@
 'use strict';
 
-const store = x => null;
+const store = x => () => x;
 
 module.exports = { store };

Exercises/3-wrapper.js

@@ -1,5 +1,23 @@
 'use strict';
 
-const contract = (fn, ...types) => null;
+const contract = (fn, ...types) => (...args) => {
+  let i = 0;
+  for (const val of args) {
+    const Type = types[i++];
+    const temp = new Type();
+    const type = typeof temp.valueOf();
+    if (typeof val !== type) {
+      throw new TypeError(`Неверный тип аргумента ${val}`);
+    }
+  }
+  const res = fn(...args);
+  const TypeRes = types[types.length - 1];
+  const tempRes = new TypeRes();
+  const typeRes = typeof tempRes.valueOf();
+  if (typeof res !== typeRes) {
+    throw new TypeError(`Неверный тип результата ${res}`);
+  }
+  return res;
+};
 
 module.exports = { contract };