Improve examples

Author: tshemsedinov

JavaScript/4-for-in.js

@@ -1,11 +1,14 @@
 'use strict';
 
 const numbers = [7, 10, 1, 5, 2];
-numbers.field = 'Value';
+numbers.field2 = 'Value2';
+numbers[-10] = 'Value3';
+numbers.field1 = 'Value1';
+numbers[5] = 20;
 
 for (const i in numbers) {
   const value = numbers[i];
-  console.log(i, value);
+  console.log(i, typeof(i), value);
 }
 
 let j, value;

JavaScript/5-for-of.js

@@ -2,6 +2,7 @@
 
 const numbers = [7, 10, 1, 5, 2];
 numbers.field = 'Value';
+numbers[7] = 5;
 
 for (const i of numbers) {
   console.log(i);

JavaScript/6-break.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const flag = true;
+const flag = false;
 
 label1: {
   console.log('Hello');
@@ -9,5 +9,7 @@ label1: {
   label2: {
     console.log('There');
     break label2;
+    console.log('Bye');
   }
+  console.log('End');
 }

JavaScript/7-continue.js

@@ -2,9 +2,9 @@
 
 let i = 0;
 
-label1: while (i < 10) {
+while (i < 10) {
   i++;
   console.log('Hello');
-  if (i === 5) continue label1;
+  if (i === 5) continue;
   console.log('World');
 }

JavaScript/8-forEach.js

@@ -1,7 +1,6 @@
 'use strict';
 
 const numbers = [7, 10, 1, 5, 2];
-
 numbers.forEach((item, i, arr) => {
   console.log(i, arr, item);
 });
@@ -12,4 +11,6 @@ numbers.forEach((item, i, arr) => {
 
 [7, 10, 1].forEach(x => console.log(x));
 
-[7, 10, 1].forEach(console.log);
+const log = x => console.log(x);
+
+[7, 10, 1].forEach(log);

JavaScript/9-map.js

@@ -1,7 +1,26 @@
 'use strict';
 
-const log = s => {
-  console.log(s);
+const log = (s, i) => {
+  console.log(i, s);
+  return s;
 };
 
-[7, 10, 1, 5, 2].map(x => x * 2).map(log);
+const f1 = x => x * 2;
+const f2 = x => ++x;
+
+const compose = (...funcs) => x => funcs.reduce((v, f) => f(v), x);
+
+const f3 = compose(f1, f2);
+
+const res1 = [7, 10, 1, 5, 2]
+  .filter(x => x > 4)
+  .map(f3)
+  .reduce((acc, val) => acc + val);
+console.log(res1);
+
+[7, 10, 1, 5, 2]
+  .map(log)
+  .map(x => x * 2)
+  .map(log)
+  .map(x => ++x)
+  .map(log);

JavaScript/a-matrix.js

@@ -7,7 +7,7 @@ const matrix = [
   [-6, 4, 8, 2, 0],
 ];
 
-const max = (a, b) => a > b ? a : b;
+const max = (a, b) => (a > b ? a : b);
 
 const res = matrix
   .map(row => row.reduce(max))