Refactor imperative to pure functional

Author: tshemsedinov

JavaScript/6-mapping.js

@@ -21,22 +21,20 @@ console.log(marcus2);
 
 // Functional
 
+const inst = (prev, prop, val) => ({ ...prev, [prop]: val });
+
 const omap = (obj, fn) => Object.keys(obj)
-  .reduce((res, key) => {
-    const [prop, val] = fn(key, obj[key]);
-    res[prop] = val;
-    return res;
-  }, {});
+  .reduce((prev, key) => inst(prev, ...fn(key, obj[key])), {});
 
 const marcus3 = {
   firstName: 'Marcus',
   middleName: 'Aurelius',
   lastName: 'Antoninus',
 };
 
-const marcus4 = omap(marcus3, (key, val) => {
-  const prop = key.toLowerCase().replace('name', '');
-  const value = val.toUpperCase();
-  return [prop, value];
-});
+const marcus4 = omap(marcus3, (key, val) => [
+  key.toLowerCase().replace('name', ''),
+  val.toUpperCase()
+]);
+
 console.log(marcus4);

JavaScript/7-chaining.js

@@ -22,11 +22,13 @@ console.log('Sum:', +sum1);
 
 const adder = initial => Object.assign(
   value => adder(initial + value),
-  { valueOf: () => initial }
+  { valueOf: () => initial,
+    map: log => log(initial) }
 );
 
 const sum2 = adder(1)(9)(1)(7);
 console.log('Sum:', +sum2);
+sum2.map(console.log);
 
 // Functional methods